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

Abstract

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 2005 to 2010. A fixed shore net (mesh <TEX>$15{\times}15\;mm$</TEX>), cast net (<TEX>$7{\times}7\;mm$</TEX>), and scoop-net (<TEX>$5{\times}5\;mm$</TEX>) were used to collect fish specimens. Changes in the fish community were not significantly different in the Nakdong River and Upo Wetlands, respectively (<TEX>$R_s$</TEX> > 0.322, N = 44, P < 0.05). Changes in the fish community between the Nakdong River and Upo Wetlands were identified as significant according to the results of cluster analysis. The relative abundance of exotic species increased 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 prevalence around all study sites. The length-weight relationship for bluegill in the Upo Wetlands was shown to have the highest values, via the formula (W = <TEX>$aL^b$</TEX>), with an average of 3.26 for the 'b' variable. According to the results of this study, lentic and lotic systems differed significantly; exotic species had an impact on both the lentic and lotic systems, but the impact of 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.