Background and objective: Fragmentation of river ecosystems is expected to affect biodiversity loss, but bridge construction is proceeding without consideration in urban areas. This study was conducted to determine the effect of internal environmental factors and river ecosystem fragmentation caused by bridge construction on the population of wintering whooper swans (<i>Cygnus cygnus</i>) in the Nakdong River of Busan Metropolitan City, a key wintering site for whooper swans.Methods: To compare the wintering population according to the distance between bridges, we surveyed and analyzed the current status of the population by period, distance between bridges, and land cover. One-way ANOVA and post-hoc test were conducted to confirm whether the differences in the environmental factors of the wintering sites, such as the distance between bridges, land cover status, and the number of wintering individuals, were statistically significant.Results: 83.6-94.7% of the wintering population in the lower Nakdong River were observed in Sec. 2 (Nakdong River Estuary Bank-Seobusan Nakdong River Bridge, 5.3 km) and Sec.4 (Gamjeon-Iron Bridge-Nakdong River Hwaengdansugwan Bridge, 3.6 km). As for the distance between the feeding and resting places of whooper swans and the bridges, whooper swans used the waterside and wetlands at an average distance of 1,147.5 m (10.9-2,611.2 m) from the bridge.Conclusion: Considering the weight of male swans and the presence of young individuals, as well as disturbance factors such as the noise and speed of vehicles crossing the bridges, it is necessary to maintain at least a 4 km distance between bridges for stable wintering. In addition, since fragmentation of river ecosystems has been confirmed to have an adverse effect on biodiversity, it would be desirable to keep the ecosystem intact and connected.

Background and objective If the <italic>Nelumbo nucifera</italic> spreads in a wetland at a high density, it can have considerable positive and negative ecological effects on habitats. For this reason, it is necessary to precisely investigate the impacts of its rapid proliferation. This study was conducted to propose the distribution and management of <italic>N. nucifera</italic>, which can cause the degradation of wildlife habitats due to the rapid spread of internal and external environmental factors that may affect the Junam wetland ecosystem. Methods For the investigation and analysis of physical and ecological characteristics, factors of the abiotic environment such as general weather conditions, topography and water depth structure, and soil and water quality analysis, and bioenvironment characteristics such as changes in the <italic>N. nucifera</italic> community distribution were evaluated. To assess whether the differences in the soil depth and physicochemical characteristics between the <italic>N. nucifera</italic> community and the aquatic plant community are statistically significant, a One-way ANOVA was executed. Results <italic>N. nucifera</italic> was presumably introduced in approximately 2007 and observed at a prevalence of only 0.8% in 2009, but had expanded to 11.1% in 2014. After that, the area was increased to 19.3% in 2015 and 40.0% in 2017, about twice that of the previous survey year. The rapid diffusion of an <italic>N. nucifera</italic> colony can have adverse effects on wildlife habitats and biodiversity at Junam Wetland. To solve these problems, four management methods can be proposed; water level management, mowing management, installation of posts and removal of lotus roots. Control of the <italic>N. nucifera</italic> community using these methods was judged to be suitable for cutting and water level management when considering expansion rate, water level variation, and wildlife habitat impacts. Conclusion As the biotic and abiotic environmental factors are different for each wetland, it is necessary to determine the timing and method of management through a detailed investigation.