Temporal Variation of Dissolved Oxygen in a Mountain Stream Plunge Pool: An Example from Northern Turkey

In this paper, a forested-mountain stream (Harmankaya) with a drainage basin about 12 km² located in Zonguldak (41°N-31°E) on the NW of Turkey has been studied associated with its plunge pools during April and November 2004. In the stream, 22 plunge pools were detected and plunge pools drop heights had a variation of 0.7–20 m, whereas average pool depths had a range of 0.53–1.59 m. In a selected pool, the variation of dissolved oxygen (DO) concentration and temperature (T_w) through the pool depth have been investigated at different time intervals. The data indicated the seasonal dependence of dissolved oxygen concentration in the plunge pool related with the water temperature and when the pool exposed to sunlight thermal stratification occurred through the pool depth. Besides, in all seasons DO levels had a downward trend from pool surface to pool bottom. Riparian vegetation significance has been emphasized in terms of the regulating the temperature and dissolved oxygen levels of a pool especially during the summer. Moreover, pool well-shaded site had relatively low degree of thermal stratification compared to waterfall impact site because of the canopy cover.