• Journal of Environmental Science International
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• v.32 no.7
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• pp.493-502
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• 2023

This study was conducted to understand the regional distribution characteristics of swans(Cygnus spp.) in downstream of t he Nakdong River , R.O.Korea from October 2008 to September 2013. During this period, a total of two species and 37,518 ind ividuals of Swans(Cygnus spp.) were observed, including 31,596 Whooper Swans(Cygnus cygnus) and 5,922 Tundra Swans (Cygnus columbianus), respectively. The average number of individuals observed in fifteen different areas was 2255.33 in D aemadeung(A), 143.50 in Jangja·Sinjado(B), 304.00 in Sajado·Doyodeung(C), 1928.00 in Lower Ulsukdo(D), 1392.67 in Ulsu kdo(E), 50.17 in Ilwoongdo(F), 91.17 in Yeommak(G), 5.17 in Maekdogang(H), 0.00 in Pyeonggangcheon(I), 0.00 in Lower Noksan sluice(J), 2.83 in Upper Noksan sluice(K), 6.17 in Jomangang·Doonchido(L), 4.50 in Chideung(M), 0.83 in Joongsado (N)and 66.17 in Daejeo sluice(O). The total average of these fifteen areas was 480.81. There was a significant difference am ong the survey areas (Kruskal-Wallis test, 𝒳²=4055.68, P<0.001). In particular, the observed numbers were larger in Dae madeung, Lower Ulsukdo and Ulsukdo than in the other regions.

• Korean Journal of Ecology and Environment
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• v.47 no.1
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• pp.62-69
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• 2014

Standing crop distribution of aquatic plants in the West Nakdong River and riparian wetlands in the Nakdong River were surveyed in May, July and September, 2010. Total 25 aquatic macrophyte species (submerged: 9, leaf-floating: 3, free-floating: 5, emergent: 8) were observed during the survey periods. Distribution area of aquatic plants and proportion of submerged communities were highest in Garakchi-deung ($212,032m^2$, 72.7%). The distribution area of aquatic plants was highest in Phragmites australis community ($421,584m^2$), followed by Hydrilla verticillata-Vallisneria natans community ($181,511m^2$), Potamogeton wrightii-Vallisneria natans community ($61,604m^2$), and Hydrocharis dubia community ($49,709m^2$). Garakch-ideung (212,032 kg) also had the highest aquatic plant production, followed by Suanchi-deung (15,546 kg), Daedong (5,813 kg), Dunchi-do (3,963 kg), Maekdo (1,463 kg), Yeommak (571 kg), Jungsa-do (530 kg), and Shinan (300 kg). Average standing crop of the study area were $147.8{\pm}20.8g\;DW{\cdot}m^{-2}$ in 1988, $96.1{\pm}20.0g\;DW{\cdot}m^{-2}$ in 2000, and $172.6{\pm}76.1g\;DW{\cdot}m^{-2}$ in 2010. For a sustainable management of river habitat and food source, aquatic plant should concurrently be surveyed with river environmental variables (i.e. sediment, nutrient, flow).

• Journal of Environmental Science International
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• v.32 no.8
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• pp.533-542
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• 2023

Understanding the regional distribution of swans in the lower Nakdong River area is also important for the continuous habitat of swans according to changes in the surrounding environment of the area. This study was conducted to understand the regional distribution aspect of swans (Cygnus spp.) downstream of the Nakdong River, Republic of Korea, from October 2013 to September 2018. In the estuary, a small ship was used to move along a certain route and observe it with the naked eye or binoculars, and in the land area, Line transect census and Point census method were conducted in parallel. During this period, two species and 34,647 individuals of swans were observed, including 34,356 Whooper Swans (Cygnus cygnus) and 291 Tundra Swans (Cygnus columbianus). The average number of individuals observed in 15 different areas was 1172, 103, 214, 1825, 1850, 13, 318, 1, 0, 1, 11, 21, 5, 0, and 239 respectively. The total average of the number of individuals in these areas was 384.76. The numbers differed significantly among the survey areas (Kruskal-Wallis test, X2=4349.01, P < 0.001). Particularly, the numbers were larger in Eulsukdo, Lower Eulsukdo, and Daemadeung than in the other regions. In conclusion, as long-term survey data, it can be used as basic data to analyze the distribution of swans due to environmental changes caused by the development of the Nakdong River, predict changes in the habitat status of migratory birds, and prepare measures necessary for preservation.