Alkali fly (Ephydra hians) productivity at Mono Lake is a valuable indicator for understanding Mono Lake’s ecosystem health. With a life cycle that occurs almost entirely within Mono Lake’s saline waters and a diet of lake algae, alkali flies and their productivity are directly linked to the environmental conditions of Mono Lake. Additionally, the alkali fly serves as the primary food source for hundreds of thousands of migratory and breeding shorebirds and waterfowl at Mono Lake.
For these reasons, the Mono Lake Committee has advocated for and facilitated alkali fly research at Mono Lake over the years. Most recently, the Committee secured grant funding through the California Department of Fish & Wildlife from the drought response provisions of Senate Bill 129 to fund alkali fly research at Mono Lake in 2024 and 2025.
Assessing Mono Lake ecosystem health
Research on the flies was part of the original ecological study of Mono Lake in 1976 when experiments were done to determine the effects of increasing salinity on the physiology of the flies. This and subsequent research identified an empirical relationship between lake salinity and alkali fly productivity, which was subsequently used by the California State Water Resources Control Board in part to determine the ecologically healthy 6,392-foot elevation.
With the lake eight vertical feet short of the Public Trust lake level 30 years after it was mandated, there is an unfortunate opportunity to better understand how elevated salinity is impairing the alkali fly population over time.
Unique research
The renewed research will be directed by one of the original alkali fly researchers from the 1976 study, Dr. David Herbst, and conducted by Committee research technician Liz Holte using lab space at the Sierra Nevada Aquatic Research Laboratory.
Holte is responsible for sampling fly larvae and pupae on the lakebed, real tufa, and artificial concrete tufa. Specimens will then be measured and categorized into one of three difficult-to-distinguish instars, or stages of development. In aggregate, this data will paint a picture of the current conditions for the flies in Mono Lake and expand the picture of alkali fly health relative to different lake levels over time.
Harvesting of kootzabe (alkali fly pupae) from the water and shoreline of Mono Lake is a traditional Mono Lake Kutzadika’a practice and the Tribe has invaluable traditional ecological and historical knowledge of the alkali flies. The Committee is coordinating opportunities for Dr. Herbst to report to and receive feedback from the Tribe about this research.
This post was also published as an article in the Summer 2024 Mono Lake Newsletter. Top photo by Robbie Di Paolo.