Evaluation of physico-chemical parameters regulating zooplankton community structure in the Geum River, Korea

The aim of the present study was to examine the dynamics of zooplankton community structure in the midstream of the Geum River, South Korea. The sampling was performed bi-monthly at five stations. During the study period, the most dominant taxa was Rotifera, comprising 73.3% of the total abundance, followed by Protozoa (17.3%), Cladocera (5.4%), and Copepoda (4.0%). The correlation coefficients between selected physico-chemical parameters and zooplankton abundance showed that the generation of zooplankton in the study area was highly correlated with water temperature (WT), chlorophyll a concentration, and pH values. As the river flows downstream (from GC and MC stations to SW, GW, and BW stations), zooplankton abundance was augmented, influenced by the levels of total phosphorus (TP), and total nitrogen (TN), while total organic carbon (TOC) decreased, and pH values increased. Furthermore, the values of WT, TN, TP, and TOC were higher and zooplankton abundance was lower at the GC station than at other stations. The results suggested that the dynamics of zooplankton community in the midstream of the Geum River was influenced not only by physico-chemical factors but also by the inflow from the upper streams.