Long-term changes in fish community and the impact of exotic fish, between the Nakdong River and Upo Wetlands

To evaluate fish community changes and the impact of exotic fish between the Nakdong River (lotic) and Upo Wetlands(lentic) using long-term ecological monitoring results, we conducted seasonal surveys of the fish community from 2005to 2010. A fixed shore net (mesh 15 × 15 mm), cast net (7 × 7 mm), and scoop-net (5 × 5 mm) were used to collect fishspecimens. Changes in the fish community were not significantly different in the Nakdong River and Upo Wetlands,respectively (Rs > 0.322, N = 44, P < 0.05). Changes in the fish community between the Nakdong River and Upo Wetlandswere identified as significant according to the results of cluster analysis. The relative abundance of exotic speciesincreased steadily during the study period, and reached 34.2% and 89.7% in the Nakdong River and Upo Wetlands, respectively,in 2010. The bluegill (Lepomis macrochirus) was used to evaluate the level of health according to prevalencearound all study sites. The length-weight relationship for bluegill in the Upo Wetlands was shown to have the highestvalues, via the formula (W = aLb), with an average of 3.26 for the ‘b’ variable. According to the results of this study, lenticand lotic systems differed significantly; exotic species had an impact on both the lentic and lotic systems, but the impactof exotic species in lentic systems was greater than in the lotic systems. Additionally, the exotic species tested herein(bluegill) adapted well in the lentic system.