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Ecoscenario: Mono Lake 4/16/03 3:18 PM Courtesy of Teri Dannenberg Negit (left) and Paoha (right) islands provide protected nesting grounds for migrating birds. BIOTIC DATA Even though it has none of the organisms you might expect to find in a lake, like fish and frogs, Mono Lake is filled with life. It is one of the most productive ecosystems in North America. The base of the food web is microscopic planktonic algae. During the winter and early spring, after the lake has turned over, bringing nutrients to the surface layer of water, algae reproduce very quickly. By March the lake is "as green as pea soup" with photosynthesizing algae. Art Explosion Blooms of planktonic and benthic algae give the water a green cast. Art Explosion Migrating birds stop at Mono Lake to eat brine shrimp and brine flies that feed on the algae. At this time countless brine shrimp hatch out of their hard-shelled cysts on the bottom of the lake. Microscopic themselves at first, they file:///Ecoscenario/mono/content.html Page 6 of 11
Ecoscenario: Mono Lake 4/16/03 3:18 PM feed eagerly on the algae, and after a few weeks they mature and produce a huge second generation of brine shrimp. In June and July, 4 or 5 trillion mature brine shrimp, each about 1 centimeter (0.4 inches) long, fill the lake. At the same time, the larvae of the brine flies (also known as alkali flies) that have been inactive on the lake bottom wake up and start eating the benthic algae that grow on the lake bottom. By midsummer, millions of brine flies are skittering across the surface of the lake. Courtesy of Teri Dannenberg California gulls feeding on brine flies at the shoreline. The darker area at the water's edge is adult brine flies. Courtesy of Teri Dannenberg Brine fly larvae and adults cover the lake bottom and the shoreline. The bounty of shrimp and flies is eaten by huge numbers of birds. Nesting birds include 50,000 California gulls (85% of California's breeding population and second largest colony in the world) and 400 snowy plovers (11% of the state's breeding population). Migratory birds include 1–2 million eared grebes (30% of the North American population), 80,000 Wilson's phalaropes (10% of the world population), 60,000 red-necked phalaropes (3% of the world population), and smaller numbers of 79 other species of water birds. Courtesy of Mono Lake Committee Courtesy of Mono Lake Committee A pair of mating brine shrimp Millions of birds feed on the trillions of brine shrimp in Mono Lake. Mono Lake is a critically important feeding stop for birds migrating south from Canada. The phalaropes and grebes arrive at the lake completely depleted of energy reserves. They linger there for several weeks, gorging on shrimp and flies until they have doubled their body weight with high-energy fats. Refueled and refreshed, they can complete their migration to Central and South America. With the departure of the last migrating birds, Mono Lake is briefly quiet. The surface is devoid of life—no flies, no birds. The lake water is clear and still. The brine shrimp ate all the algae, and in turn were eaten by the migratory birds. The brine shrimp egg cysts lie waiting on the lake bottom with the dormant larvae of the brine flies. The chill of autumn closes in, and Mono Lake gets cold. Then the lake turns over for the 760 thousandth time, and the few remaining algae respond. The cycle repeats. ISSUES There is really only one issue at Mono Lake...fresh water. Life depends on it in Mono Lake as surely as it does in every other ecosystem file:///Ecoscenario/mono/content.html Page 7 of 11
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