Hyo Jeong Kang

Is median nerve enlargement at the wrist associated with tremor in Parkinson disease

Tremor is one of the cardinal features of Parkinson disease (PD) and may cause cumulative trauma‐related injury to nerves of the hands. The aim of this study was to assess the electrodiagnostic and sonographic features of patients with PD and to assess the effect of tremor in PD on the median nerve.

Drought effects on the colonization of benthic macroinvertebrate communities in the early successional phases in experimental mesocosm wetlands

We investigated the drought effects on the colonization rate and pattern of benthic macroinvertebrate communities in newly created mesocosm wetlands in the central Korean Peninsula, from June 2011 to June 2013. The comparison was made between the initial colonization after mesocosm construction (pre-drought) and the recolonization after a drought event (post-drought) with a drought period of 50 days between them. In addition, we categorized communities according to their biological traits in relation to drought. Our results showed that aquatic vegetation abundance and covering degree were higher in post-drought than in pre-drought, thereby influencing rapid colonization. Drought-resistant benthic macroinvertebrates colonized rapidly in post-drought; consequently, the colonization speed was 2.5-fold higher in post-drought than in pre-drought. We classified the benthic macroinvertebrate taxa into three groups: (1) a resistant group which generally emerged after the initial colonization period (e.g., Mollusca, Turbellaria, and Oligochaeta); (2) a sensitive group with diverse life history strategies and biological traits such as active migration or population decline after drought disturbance (e.g., Diptera: Chironominae, Odonata: Orthetrum, Coleoptera: Agabus and Rhantus); and (3) a seasonal group, which emerged only during certain periods and were not markedly influenced by drought (e.g., Ephemeroptera: Cloeon, Diptera: Culicidae, Odonata: Zygoptera and Pantala). Our findings elucidated the effects of drought on benthic macroinvertebrate communities in wetlands by using a mesocosm experiment.

Temporal changes in benthic macroinvertebrates and their interactions with fish predators after restoration in the Cheonggyecheon, a downtown stream in Seoul, Korea

The Cheonggyecheon (Cheonggye stream), a downtown stream in Seoul, Korea, was restored by the historic Cheonggyecheon Restoration Project (2003–2005), and its discharge and other environmental conditions are artificially regulated throughout the year. The aim of this study was to assess temporal changes in benthic macroinvertebrates and their interactions with fish predators in the Cheonggyecheon. Sampling was conducted twice a year (spring and autumn) at three sections of the stream from 2006 to 2010 using a Surber sampler (50 × 50 cm) for benthic macroinvertebrates and a cast net (mesh size, 10 × 10 mm) and a kick net (mesh size, 5 × 5 mm) for fishes. Analyses of annual precipitation and most water quality parameters showed no significant differences across the study period (P > 0.05). The species richness and density of benthic macroinvertebrates and fishes varied across the sampling period. Analyses of functional feeding groups and trophic guilds showed distinct trends, such as an increase in the number of insectivorous fish in the absence of invertebrate predators. Correlation and regression analyses for five major groups of benthic macroinvertebrates and fishes demonstrated that the density of certain groups of benthic macroinvertebrates (e.g. Tubificidae, Erpobdellidae, Baetidae, and Chironomidae) and insectivorous fishes (e.g. Gobioninae, Leuciscinae, Danioninae, and Gobiidae) were negatively correlated. In conclusion, in an artificially regulated stream like the restored Cheonggyecheon, where physical environments are nearly unchanged, fish predation can be a major factor controlling benthic macroinvertebrate communities.

Four-year successive rearing of Glyptotendipes tokunagai Sasa (Diptera: Chironomidae) under laboratory condition

The dipteran Chironomidae have been commonly used as water quality indicators and toxicity test organisms. Two chironomids, Chironomus riparius Meigan and C. tentans Fabricius, are standard test organisms for toxicity (OECD), but their distribution is limited in Korea. The purpose of this study was to establish a Korean native chironomid species as a toxicity test organism. Glyptotendipes tokunagai Sasa, distributed widely in Korean streams, was selected and reared successively under laboratory conditions for over 30 generations over 4 years.

Biological and Genetic Characteristics of Glyptotendipes tokunagai (Diptera: Chironomidae) on the Basis of Successive Rearing of Forty-Two Generations Over Seven Years Under Laboratory Conditions

ABSTRACT Members of the nonbiting midge family Chironomidae have been used worldwide as water-quality indicators or toxicity test organisms. The purpose of this study was to establish the chironomid Glyptotendipes tokunagai Sasa as a new test species by conducting successive rearing under laboratory conditions. We monitored biological and genetic aspects of >42 successive generations over 7 yr, and also compared the development of the 39th generation with the fourth generation under five constant temperatures of 15, 20, 25, 30, and 35°C. We observed that the number of eggs in an egg mass and the adult body sizes decreased rapidly in the early generations, and thereafter tended to stabilize from the fifth generation to the 42nd generation. In all generations, the mean hatching rate was >75%. Males were predominant in the early generations, but the sex ratio increased to 0.5 (ranged 0.24–0.61) in later generations. The genetic divergence of the reared generations, analyzed by using the mitochondrial cytochrome c oxidase subunit I gene, decreased from 0.0049 to 0.0004 as the generations progressed. In comparison with the fourth generation, the mortality and developmental time of the 39th generation were generally greater, and the adult body sizes were generally smaller. The estimated low developmental threshold temperatures of eggs, male larvae to male adults, and female larvae to female adults were 9.6, 11.3, and 9.7°C, respectively. The optimal rearing temperature was determined to be 25°C. This is the first record of domesticated rearing of a wild chironomid species under laboratory conditions for >7 yr.

One New Species and Three New Korean Records of the Orthocladiinae (Diptera: Chironomidae)

The non‐biting midge subfamily Orthocladiinae (Diptera: Chironomidae) are a common and abundant insect group inhabiting diverse freshwater habitats. The subfamily contains approximately 1,500 species worldwide including 606 Japanese, 118 Chinese, and 166 Far East Russian species. Since the 1980s, 25 Orthocladiinae species have been recorded in Korea by several Korean chironomid taxonomists. In this study, one new species and three new Korean records of the subfamily are presented: Smittia n. sp., Corynoneura longipennis Tokunaga, Smittia akanduodecima Sasa and Kamimura, and Smittia pratora (Goetghebuer). Descriptions of male adults, line drawings, and diagnoses are provided.

A long‐term change of benthic macroinvertebrate communities in the Cheonggye stream, a restored urban stream in Seoul, Korea

Stream restoration affects stream biodiversity by improving water quality and habitat environments. Benthic macroinvertebrates are used as indicators of changes in stream environment, and, therefore, the effects of restoration can be evaluated by a long‐term monitoring of benthic macroinvertebrates. Cheonggye stream is an urban stream in Seoul, Korea, and a restoration project was conducted from July 2003 to September 2005. The purpose of this study was to investigate the long‐term changes in the benthic macroinvertebrate communities in Cheonggye stream after the restoration project in 2005.

Long‐term monitoring of the life history of a riverine mayfly Ephemera orientalis (Ephemeroptera: Ephemeridae) in the Han River in Seoul, Korea

Climatic change often affects life history aspects of aquatic insects. Long‐term monitoring was conducted to understand the life history variability of the riverine mayfly Ephemera orientalis in the Han river, where habitat is largely disturbed by summer floods. Water level of the study site, Godeok‐dong area in Seoul, is regulated by the Paldang Dam located approximately 14 km above the study site. E. orientalis often emerged in large numbers around the study area. Larvae were sampled monthly from April 2006 to July 2010 using a Surber sampler (50 × 50 cm, mesh 0.25 mm, two replicates). Additional qualitative sampling was conducted using a hand net. As a result, based on the larval body size distribution, E. orientalis had a univoltine life cycle with two distinct slow growing cohort groups: the S1group emerged during May–June and the S2 group emerged during August–September. Our previous study conducted in Gapyeong stream in Gyeonggi‐do showed that E. orientalis normally had three cohort groups, S‐1 and S‐2 groups and the F‐group (a fast growing cohort developed during May–August). However, the Han River population of E. orientalis lacked such a fast growing cohort. It is most probable that habitat disturbances caused by high water level during the rainy season negatively affected the development of the fast growing cohort (F‐group) in the Han River area. The relationships between monthly E. orientalis population data and water level in the Han River are presented.