Benthic macroinvertebrates, that are sensitive to water pollution, are important indicators in determining health status of stream ecosystems. Wu Gou Shui is located in an area with upwelling of groundwater and suitable to study the relationship between hyporheic zone and stream environmental condition, such as physical, chemical, and biological variables. This research was conducted during the March to May 2012 at Wu Gou Shui area, Pingtung County, Taiwan. Benthic macroinvertebrates were collected with kick sampling and Surber sampler methods. Chemical (DO, pH, electric conductivity, turbidity, and chlorophyll a) and physical (flow velocity, water depth, and gravel composition) environmental conditions were also measured to compare with the macroinvertebrate data. Up-welling and down-welling groundwater were determined by using a minipiezometer along Wu Gou Shui and later to be analyzed their relationships to environmental variables. Abundance of benthic macroinvertebrates was positively correlated with flow velocity and negatively correlated with water depth. Number of taxa was positively correlated with flow velocity. Abundance of mayflies was negatively correlated with water depth. The vertical hydraulic gradient (VHG) was negatively correlated with water depth and electric conductivity but positively correlated with DO.

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