When you think of a lake ecosystem, what do you think of? A large, blue lake teeming with life: fish, water plants; things like that? 

Mono Lake defies all these standards we pictured in our minds. It has no fish, and strange alien-like rock towers. However, it supports one of the most unique and most productive ecosystems.

Mono Lake is a huge ancient lake on the edge of the arid Great Basin and snowy Sierra Nevada mountains in the state of California. It is 2,000m above sea level. Mono Lake has no outlet to the ocean, and therefore dissolved salts remain stuck in the lake - making Mono Lake a saline lake. pH levels of the lake as well as salt concentrations are high.

Although the high salt concentration makes the lake inhabitable for fish species, the lake is home to trillions of brine shrimp and alkali flies, as well as millions of birds. The alkali flies are particularly interesting as well as being important for the food chain; tiny hairs on the flies trap air, allowing them to swim underwater. The brine shrimp that feed on these flies (and provide food for migratory birds) live only in Mono Lake - nowhere else on this planet. 50,000 California gulls call the lake islands home.

The alien-like rock towers cannot go unmentioned; they are a vital part to Mono Lake’s ecosystem. The tufa towers provide nesting sites for ospreys and owls, along with underwater habitats for alkali flies. How do they form though, and what exactly are they? Mono Lake’s tufa towers form underwater, when calcium from lake bottom springs chemically reacts with the carbonate-rich water and forms a precipitate (a formed separated solid). Over decades or centuries, the tufa towers can grow to about 30 feet.  

Mono Lake has been strongly threatened by water diversion. In order to meet increasing water demands in Los Angeles, Mono Lake’s tributary streams began to be diverted in 1941. The lake level dropped by 45 feet, and revealed the tufa towers (that can only grow underwater). A group of students, after studying the lake in 1976, discovered the incredible ecosystem of the lake, and moved to protect the lake. 

Today, Mono Lake is protected as a reserve. I had the pleasure of visiting last month on a road trip; there were many flies crowding the lakeshore. The water was extremely salty, but it was beautiful.

If you ever find yourself in the Sierras, be sure to check out this special ecosystem!

References used:

https://www.monolake.org/

https://www.globalnature.org/en/mono-lake

(attached) personal photo