Understanding biotic interactions is important to illustrate ecological functions of stream environments. The purposeof this study is to compare the ecological functions of natural and artificial streams. For linking species, we used bioticinteraction databases and made food-webs for species lists of 18 streams in Seoul, Korea. We conducted species removalanalysis of networks and compared network beta-diversity between watersheds. The results showed that natural streamswere more affected by a removal of keystone species than artificial streams. The cheonggye watershed including artificialstreams had high dissimilarities among streams, presenting that artificial streams had different functions from natural streams.