Longitudinal patterns in limnological characteristics based on long-term ecological research in the Nakdong River

In 2004, the Korean Ministry of Environment initiated the National Long Term Ecological Research (LTER) program. Wehave attempted to analyze longitudinal patterns in limnological aspects based on LTER monitoring data collected fromJune 1994 to May 2008 in the Nakdong River, a regulated river ecosystem. Factor analysis, a multivariate ordination statisticalmethod, was employed. Relationships among measured parameters were evaluated at different sites of the river.Overall, the trophic state of the Nakdong River was hyper-trophic (total nitrogen, 3.5-4.8 mg/L; total phosphorous, 57-95μg/L; chlorophyll a, 15.2-38.5 μg/L). Among the three study sites, recurrent algal blooms consistently appeared in thelower reaches of the river. Extracted factors revealed different patterns, particularly for chlorophyll a concentration, anda rigid separation of limnological patterns was found at site 3 (Mulgeum) based on the factor analysis. From the results,more sustained observations through LTER will be helpful to manage and conserve ecosystems in the future. Furthermore,recent issues regarding ecosystem dynamics such as water quality with respect to global climate change requirelong-term datasets. Information collected by the LTER approach is hereby indispensable for ecological characterization.