Description of Artemia monica
Global Range: (100-250 square km (about 40-100 square miles)) Endemic and only inhabits one terminal lake (Mono Lake, Mono Co., California).
endemic to a single state or province
Regularity: Regularly occurring
Type of Residency: Year-round
Similar to Artemia franciscana but does not co-occur. Only in Mono Lake. Cyst similar to A. franciscana in size (mean 0.19 mm) but Artemia monica cysts sink when released, do not require a period of desiccation, do need 1-3 months of cold water incubation before hatching in March (Eriksen and Belk, 1999).
Habitat and Ecology
Habitat Type: Freshwater
Comments: Endemic and only inhabits one terminal lake (Mono Lake, Mono Co., California) with elevated concentrations of salt. This is North America's oldest lake (500,000 years) with high TDS 76,000 ppm (1967) to 93,600 ppm (1988), pH 9.7, and extremely high alkalinity at 19,500 ppm (1967) to 36,700 ppm (1988) (Eriksen and Belk, 1999).
Non-Migrant: Yes. At least some populations of this species do not make significant seasonal migrations. Juvenile dispersal is not considered a migration.
Locally Migrant: No. No populations of this species make local extended movements (generally less than 200 km) at particular times of the year (e.g., to breeding or wintering grounds, to hibernation sites).
Locally Migrant: No. No populations of this species make annual migrations of over 200 km.
Number of Occurrences
Note: For many non-migratory species, occurrences are roughly equivalent to populations.
Estimated Number of Occurrences: 1 - 5
Comments: This species is represented by only one known occurrence.
Comments: An estimated 4-6 trillion brine shrimp inhabit the lake during the warmer summer months.
IUCN Red List Assessment
Red List Category
Red List Criteria
- Needs updating
- 1994Indeterminate(Groombridge 1994)
- 1990Indeterminate(IUCN 1990)
- 1988Indeterminate(IUCN Conservation Monitoring Centre 1988)
- 1986Indeterminate(IUCN Conservation Monitoring Centre 1986)
National NatureServe Conservation Status
Rounded National Status Rank: N3 - Vulnerable
NatureServe Conservation Status
Rounded Global Status Rank: G3 - Vulnerable
Reasons: This species is endemic to Mono Lake in California and an estimated 4-6 trillion brine shrimp inhabit the lake during the warmer summer months. It has no major threats now or in the foreseeable future and is stable, but since there is only one population from a single lake, this species is ranked as vulnerable.
Intrinsic Vulnerability: Highly vulnerable
Comments: Highly endemic and cannot live in any other lake (alkalinity too low) in California (Eriksen and Belk, 1999), although the lake is fairly large and deep.
Global Short Term Trend: Relatively stable (=10% change)
Comments: Stable population over time despite changes in lake dynamics.
Global Long Term Trend: Unknown
Degree of Threat: Low
Comments: This species has no known threats, however there are several environmental factors that can affect development, survival and reproduction of the Mono Lake brine shrimp: temperature, salinity, dissolved oxygen, and food supply (see the Mono Basin EIR for discussion).
The shrimp population appears to be unaffected by either bird predation or commercial harvest.
A 1987 petition to add A. monica to the endangered species list based on the threat of rising salinity and concentration of sodium hydroxide in Mono Lake was found in 1995 to not be warranted (USFWS 1995).
Biological Research Needs: Continue long-term limnological monitoring in Mono Lake. Study the effects of temperature, salinity, dissolved oxygen, and food supply on development, survival and reproduction of Artemia monica.
Global Protection: None. No occurrences appropriately protected and managed
Comments: A 1994 decision by the California State Water Resources Control Board now protects the ecological values of Mono Lake. Since the 1940's, the lake's increasing salinity substantially reduced brine shrimp reproduction, and the existence of the species could have been threatened if the lake level continued to decline. A 1994 decision by the Water Resources Control Board reduced Los Angeles' water rights and established a target lake level of 6,392 feet elevation, with an estimated salinity of 69 parts per thousand. As a result, the USFWS determined that the lake conditions established by the Board provided adequate protection for the long-term existence of the Mono Lake brine shrimp. The target lake level incorporates an adequate buffer to protect the brine shrimp and other components of the ecosystem from extreme salinity during prolonged drought.
Needs: Continue to protect Mono Lake. Mono Basin restoration is aimed at restoring natural processes and ecological function. Raising the level of the lake will lower its salinity, reduce dust storms and reconnect the lake to springs and deltas. Reinstating stream flows that mimic natural flows, particularly the annual spring flood, will provide the dynamic energy needed to rebuild deep stream channels and pools, re-grow riparian forests and reestablish healthy floodplains (Mono Lake Committee 2013).
Manage water in Mono Lake in more environmentally sound ways.
Relevance to Humans and Ecosystems
Stewardship Overview: Mono Basin restoration is aimed at restoring natural processes and ecological function. Raising the level of the lake will lower its salinity, reduce dust storms and reconnect the lake to springs and deltas. Reinstating stream flows that mimic natural flows, particularly the annual spring flood, will provide the dynamic energy needed to rebuild deep stream channels and pools, re-grow riparian forests and reestablish healthy floodplains (Mono Lake Committee 2013).
Manage water in Mono Lake in more environmentally sound ways.
Names and Taxonomy
Comments: Probably evolved from a population of Artemia franciscana in Mono Lake (Eriksen and Belk, 1999). There are differing views on whether A. franciscana and A. monica are sibling species; furthermore, there are no taxonomic identification keys for the genus due to a lack of reliable morphological characters (Asem et al. 2010).
All Artemia were formerly considered to belong to a single species, Artemia salina, but were divided into several closely related species by Bowen et al. (1980). However, there is taxonomic confusion with numerous published data using the trade name "Artemia salina" for any population in this genus (Asem et al. 2010).