Colonization and community changes in benthic macroinvertebrates in Cheonggye Stream, a restored downtown stream in Seoul, Korea

Colonization patterns and community changes in benthic macroinvertebrates in the Cheonggye Stream, a functionallyrestored stream in downtown Seoul, Korea, were studied from November 2005 to November 2007. Benthic macroinvertebrateswere quantitatively sampled 15 times from five sites in the stream section. Taxa richness (59 species in total)increased gradually over the first year, whereas the density revealed seasonal differences with significantly lower valuesin the winter season and after flood events. The benthic macroinvertebrate fauna may have drifted from the upstreamreaches during floods and from the Han River, arrived aerially, or hitchhiked on artificially planted aquatic plants. Oligochaeta,Chironommidae, Psychodidae, and Hydropsychidae were identified as major community structure contributorsin the stream. Swimmers and clingers colonized relatively earlier in the upper and middle reaches, whereas burrowersdominated particularly in the lower reaches. Collector-gatherers colonized at a relatively early period throughout thestream reaches, and collector-filterers, such as the net-spinning caddisfly (Cheumatopyche brevilineata), predominatedin the upper and middle reaches after a 1-year time period. Cluster analyses and multi-response permutation proceduresdemonstrated that the Cheonggye Stream shares more similarities with the Jungnang Stream than with the GapyeongStream. Detrended correspondence analysis and nonmetric multidimensional scaling demonstrated that physicalenvironmental factors (depth, current velocity, dissolved oxygen, and pH) as well as nutrients (total nitrogen and totalphosphorous), water temperature, and conductivity could affect the distribution of benthic macroinvertebrates in thestudy streams.