Throughout most of the year wind and tidal mixing bring much needed dissolved oxygen to the Sound’s bottom waters. However, rising summer temperatures coupled with increased respiration from microbes (a consequence of excess nitrogen in the water) can deplete the bottom layer, resulting in summer hypoxia (dissolved oxygen levels below 3 mg/L). The increasing temperatures also limit the diffusion of oxygen to the bottom waters and the amount of oxygen the bottom layer can hold. The resulting hypoxia stresses fish and other wildlife. Toward the late summer, when temperatures start to cool and winds mix the surface and bottom waters, oxygen levels rebound. Open the story map prepared by the Connecticut Department of Energy and Environmental Protection to see a time series of monthly changes to the oxygen levels of the Sound in 2014.