the lake replenishes over the next 20 years. An unintended consequence of ending the water diversions was the onset of a period of "meromixis" in Mono Lake. In the time prior to this, Mono Lake was typically "monomictic"; which means that at least once each year the deeper waters and the shallower waters of the lake mixed thoroughly, thus bringing oxygen and other nutrients to the deep waters. In meromictic lakes, the deeper waters do not undergo this mixing; the deeper layers are more saline than the water near the surface, and are typically nearly devoid of oxygen. As a result, becoming meromictic greatly changes a lake's ecology. Mono Lake has experienced meromictic periods in the past; this most recent episode of meromixis, brought on by the end of the water diversions, commenced in 1994 and had ended by 2004. Ecology Aquatic life The hypersalinity and high alkalinity (pH=10 or equivalent to 4 milligrams of NaOH per liter of water) of the lake means that no fish are native to the lake. An attempt by the California Department of Fish and Game to stock the lake failed. The whole food chain of the lake is based on the high population of single-celled planktonic algae present in the photic zone of the lake. These algae reproduce rapidly during winter and early spring after winter runoff brings nutrients to the surface layer of water. By March the lake is "as green as pea soup" with photosynthesizing algae. The lake is famous for the Mono Lake brine shrimp, Artemia monica, a tiny species of brine shrimp, no bigger than a thumbnail, that are endemic to the lake. During the warmer summer months, an estimated 4–6 trillion brine shrimp inhabit the lake. Brine shrimp have no food value for humans, but are a staple for birds of the region. The brine shrimp feed on microscopic algae. Alkali flies, Ephydra hians, live along the shores of the lake and walk underwater, encased in small air bubbles for grazing and to lay eggs. These flies are an important source of food for migratory and nesting birds. 8 Nematode species were found living in the littoral sediment: Auanema spec., which is outstanding for its extreme arsenic resistance (survives concentrations 500 times higher than humans), having 3 sexes, and being viviparous. Pellioditis spec. Mononchoides americanus Diplogaster rivalis species of the family Mermithidae Prismatolaimus dolichurus 2 species of the