The oxygen depletion in worldwide oceans and inland waters is becoming an increasingly prevalent problem. Here, two comparative study sites, Baltic Proper (BP) and Shuikou Reservoir (SR), were selected to identify the dynamics of dissolved oxygen (DO) and the related physicochemical response by conducting five field investigations over one year period. The DO concentrations were 0–9.9 mg L−1 and 0.3–8.7 mg L−1 in BP and SR, wi...