• Korean Journal of Environment and Ecology
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• v.30 no.5
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• pp.888-895
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• 2016

The population ecology (Ecological characteristics) of Squalidus chankaensis tsuchigae were investigated at Geum River from March to November, 2013. This species inhabited midstream of the river where was mostly covered with cobble and sand. The depth of the habitat was 30~60 cm and velocity of stream was 2.27~4.88 cm/sec. The sex ratio of female to male was 1 : 0.86. They were sexually mature when they were over two years of age. The spawning period was from June to July with water temperatures from $25^{\circ}C$ to $25^{\circ}C$. Sexually matured individuals appeared over the two year of age. Frequency analysis of total length indicated that the group with 55~70 mm in total length was one year old, the 71~90 mm was two years old, and the group over 91 mm was three years old. The average number of eggs in the ovaries was estimated as 2,219 per matured female. The number of matured eggs size in ovaries was 0.64~0.98 (mean: 0.85) mm. Calulation length-weight relation of S. chankaensis tsuchigae show the value of contant a as 0.0002 and b as 2.81, and condition factor (K) was 1.06 on average. The stomach contents were Cyanophyta, Chlorophyta, Bacillariophyta, Crustaceae, Copepoda, Nematota, Actithocephala, and Ephemeroptera, Hemiptera, Diptera, and Trichoptera that belong to Aquatic insect, and dormant bud of Pectinatella that belongs to Phylactolaemata. The diet of S. chankaensis tsuchigae was omnivorous, mainly vegetable feed on attached algae (filament form), and mainly animality feeded on benthic invertebrates such as Chironomidae larvae.

• Journal of Environmental Science International
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• v.12 no.11
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• pp.1181-1187
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• 2003

Hibiscus hamabo, called "Hwang-geun", growing about 3m in height is a deciduous shrub or subtree of Malvaceae. Because the number of these species is very limited in the world, the Ministry of Environment has designated H. hamabo as a preserved plant. The Korea Forest Service also protects it strictly by law since H. hamabo is an out-of-the-way plant and possibly may be exterminated soon in Korea. Investigation for distribution and ecological characteristics of the habitat for H. hamabo was carried out on Soan Island. Two wild H. hamabo were found at the forest edge (equation omitted) along the sea coast located in the southern part of Soan Island and this was the first report in the Korean academic world. These two wild H. hamabos were growing in a naturally inhibited area. The diameters at the base were 12cm and 15cm. The Tree heights were 150cm and 210cm and the number of branches of each wild H. hamabo was 4 and 7. However, the present condition of these plants was not good. Environmental conditions of the naturally inhibited area of H. hamabo were very mild because it is located at the edge of the forest and is always sunny during the daytime since the slope of the inhibited area is facing South. The ground drained very well since the soil was made of gravels and sand. Because the percent of vegetation of the subtree layer where H. hamabo was growing was 40%, the cover degree and sociability of flex crenata trees and Eurya japonica were found to be high. In the naturally inhibited area of H. hamabo, a dominant value of Rubus parvifolius in the lower part of the herb layer was very high and many plants in Compositae, such as Artemisia princeps var. orientalis and Erigeron annuus, were also present. A dominant value of liana, such as Vitis thunbergii var. sinuata, Rosa multiflora, Clematis terniflora and Hedera rhombea, and Gramineae plants that rhizomes were well developed and aggressively propagated, such as Miscanthus sinensis var. purpurascens, Phragmites communis, Spodiopogon cotulifer and Oplismenus undulatifolius which were surveyed as high, too. These results imply that H. hamabo might be exterminated soon through a natural selection if the proper management of the naturally inhibited area of H. hamabo is not conducted continually.

• Korean Journal of Organic Agriculture
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• v.26 no.2
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• pp.297-316
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• 2018

The golden apple snail (GAS, Pomacea canaliculata) is an invasive freshwater snail. The GAS was introduced in Korea without prior studies on the possibility of crop damage or its impact on the natural ecosystem. The freshwater apple snails can be found typically in ponds, rice paddies, irrigation canals, roadside ditches or slower portions of streams. In this study, we were carried out to investigate the assessment of physiological and ecological characteristics, environmental characteristics inhabited area in winter season and cause of massive death at one time of golden apple snails used for weed control in wet rice paddies. The GAS was introduced from Japan to Korea for commercial production as a dietary protein supplement. The golden apple snail was also used a recently for weed control in wet rice cultivation. The species of freshwater Pomacea snails is belonging to the genus Pomacea, family ampulariidae, order mesogastropoda, subclass pulmonata, class gastropoda, phylum mollusca. The GAS spread into irrigation ditches and natural waterways. It is now distributed in ponds and canals near rice fields of southern parts of the country and has overwintered. It increases its cold hardiness before winter. However, the physiological mechanism of cold hardiness in molluscs is poorly understood, especially in freshwater molluscs. Our results on physio-ecological characteristics of the Pomacea apple snail showed that the ratio of males to females was 1: 1.99~2.33. The daily growth was 87.7 mg in weight, 0.31 mm in height and 0.33 mm in width of the their shell. On the other hand, the golden apple snails were very high to resistance on drying condition and survived rate about 80% up to 3 months. The inhabitation of GAS was no statistical significant impacts on the water quality. An important property of aqueous solutions is agricultural water quality because it affects chemical and biochemical properties such as chemical reactions, equilibrium conditions, and biological toxicity. The death rate of weed control apple snails by Ostracoda (Stenocypris hislopi) was only 2.86% and 5.71% depending on the density. Therefore, GAS was not a direct death caused by Ostracoda (Stenocypris hislopi).

• Journal of Environmental Impact Assessment
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• v.25 no.5
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• pp.319-332
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• 2016

Alien turtles belonging to Genus Trachemys have been designated as Invasive Alien Species since 2001 and their import has been banned in Korea. However, current status of import and distribution of the other alien turtles have not been reported. In this study, we aimed to investigate the taxa of alien turtles introduced into Korea, to assess their potential risks to the natural ecosystems and to suggest the future management directions of them in Korea. We identified 73 species of alien turtles belonging to 9 families. Since 2008, more than 6,000 kg of turtles have been imported annually and widely distributed through the pet shops, traditional markets and individual transactions. From the survey of natural habitats, we found that 8 species belonging to 3 families including Chrysemys picta, Pseudemys concinna, P. nelsoni, P. peninsularis, P. rubriventris, Mauremys sinensis, Macrochelys temminckii and Trachemys scripta have inhabited in 12 study sites. Out of 73 alien turtles, the potential adverse impacts of 13 species to ecosystems are serious when we considered status of designation of invasive alien species in other countries. For the management of alien turtles, it is required to register alien turtles in the import list and share general information such as import purpose, distribution and management condition among relevant authorities. The breeders and distributors must be obliged to identify turtles and to record management. The government must check transfer and migration of turtles periodically to prevent their introduction and spread into natural environments. The change of alien turtle populations in natural habitats should be monitored and their management plan should be developed to control the alien turtles in areas where the impacts are significant.

• Korean Journal of Environment and Ecology
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• v.36 no.6
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• pp.627-638
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• 2022

This study was conducted at a village fishing farm on 4 peaks on the main island of Jeju Island and 2 peaks on an inhabited island to compare the distribution characteristics of seaweeds along the coast of Jeju Island from May to December 2018. A total of 101 species of seaweeds were surveyed, including 13 species (12.9%) of green algae, 24 species (23.8%) of Phaeophyta, and 64 species (63.4%) of Rhodophyta. The largest number of seaweeds appeared in May and the fewest in October, showing typical features of a temperate sea area. The number of seaweed species that appeared was 66 and 65 species at the water depths of 5 m and 8 m, respectively, and the largest was 74 species at 12 m. The number of seaweeds that appeared by area was the largest at 66 species on Udo Island, an eastern island near Jeju Island, and the lowest at 27 species in Pyoseon-ri, an eastern part of Jeju Island. The important values of emerging species were high in the order of, Ecklonia cavaand Corallina crassissima at 21.1% and 20.3%, respectively, Corallina aberransat 9.2%, Amphora ephedraeaat 6.2%, and Sargassum macrocarpumat 4.4%. Among seaweeds, an average of 11.2 species of coralline algae appeared, and the mean importance value was 32.6% in the sear area. The lowest importance value was 14.7% on Udo Island, and the highest was 41.0% in Pyoseon-ri. The mean ecological evaluation index (EEI) of seaweed colonies ranged from 2.1 to 10. It was the lowest at the water depth of 12 m in Pyoseon-ri in May and June and was 7.3 or higher in other areas, indicating good condition. This study rated the standardized ecological grade I for the water depth of 12 m on Udo Island and grade II for the water depths of 5 m and 8 m in Sagye-ri and on Chujado Island. Grade III was the water depth of 5 m and 12 m in Pyoseon-ri and Guideok 2-ri and the water depth of 5 m and 8 m in Pyeongdae-ri, and grade IV was the water depth of 8 m in Guideok 2-ri.