As a contributor to the formation of ground-level ozone, nitrogen dioxide can have adverse effects on both land and water ecosystems. Along with sulfur dioxide, nitrogen oxides in the air can significantly contribute to acid rain. NO2 and other NOx gases also can enter bodies of water and lead to eutrophication, a process whereby excess nitrogen causes explosive overgrowth of algae and weeds in lakes, estuaries and slow-moving streams. The "bloom" and subsequent decomposition of plants reduce water quality and dissolved oxygen in the water to stress or kill fish and other wildlife.