|Scientific Name:||Cambarellus prolixus Villalobos & Hobbs, 1981|
|Red List Category & Criteria:||Critically Endangered B1ab(iii) ver 3.1|
|Assessor(s):||Alvarez, F., López-Mejía, M. & Pedraza Lara, C.|
|Reviewer(s):||Collen, B. & Richman, N.|
|Contributor(s):||Livingston, F., Livingston, F., Soulsby, A.-M., Batchelor, A., Dyer, E., Whitton, F., Milligan, H.T., Smith, J., Lutz, M.L., De Silva, R., McGuinness, S., Kasthala, G., Jopling, B., Sullivan, K. & Cryer, G.|
Cambarellus prolixus has been assessed as Critically Endangered under criterion B1ab(iii). This species has an extent of occurrence of approximately 40 km2, and is known from only one location. Furthermore, this species is experiencing a continual decline in quality of habitat, as a result of water abstraction, sedimentation and pollution. These threats are assumed to have resulted in a decline in the population of this species. Monitoring of the population numbers of this species is needed to better determine how this species is affected by mentioned threats. If the population is in fact found to be stable then this species would qualify for listing as Near Threatened.
|Range Description:||This species is known only from Lake Chapala, Jalisco, Mexico (Hobbs 1989). This lake has a surface area of 1,100 km2 (Villalobos-Figueroa and Hobbs 1981) and is at an altitude of approximately 1,520 m above sea level (Lind and Davalos-Lind 2002). Villalobos-Figueroa and Hobbs (1981) mapped the distribution of this species within Lake Chapala, and from this, the species is estimated to have an extent of occurrence of approximately 40 km2.|
|Range Map:||Click here to open the map viewer and explore range.|
|Population:||At a depth of 3 - 5 m this species has been described as relatively common (C. Pedraza-Lara pers. comm. 2009).|
|Current Population Trend:||Unknown|
|Habitat and Ecology:||This species is known only from Lake Chapala, where it occupies the marginal and sub-marginal zones (Villalobos-Figueroa and Hobbs 1981). It usually occurs at depths of 3 - 4 m, but individuals have been found down to 8 m (Villalobos-Figueroa and Hobbs 1981). The water temperature in these regions is 18.0 to 20.5oC with transparency of 1.2 to 1.4 m, oxygen concentrations of 4.44 to 4.66 ml/L, and a pH of between 8.3 to 8.6 (Villalobos-Figueroa and Hobbs 1981).|
|Continuing decline in area, extent and/or quality of habitat:||Yes|
Lake Chapala is severely threatened by water abstraction, sedimentation and pollution. Over the last 20 years, the lake has experienced a 3 m drop in surface level, a 42 % reduction in water volume and an 8 % reduction in surface area (Lind and Davalos-Lind 2002). This has occurred largely as a result of increased water abstraction for agriculture, and to meet the needs of the growing population in Guadalajara, Mexico's second-largest city, which uses the lake as its primary water source (Lind and Davalos-Lind 2002). In addition, the depth of the lake has been further reduced by increased sedimentation caused by changes in land-use in the surrounding valley (Lind and Davalos-Lind 2002). Increased sediment flow into the lake has also resulted in reduced light availability, limiting photosynthetic production (Lind and Davalos-Lind 2002). However, due to the large amount of domestic and agricultural waste it receives, the lake is nutrient-rich, so in shallower areas, where light is less limiting, algal blooms are common (Lind and Davalos-Lind 2002). The lake also receives a considerable amount of industrial waste (Lind and Davalos-Lind 2002). Concentrations of cadmium and lead above the freshwater chronic criteria values recommended by the United States Environmental Protection Agency for protection of aquatic ecosystem health have been recorded, and the lake also contains significant concentrations of arsenic, chromium, zinc, nickel and copper (Shine et al. 1998).
A study by Lyons et al. (1998) revealed that, of the 44 species of fish endemic to Lake Chapala and the Lerma drainage basin, 3 are now extinct and 23 have greatly reduced ranges and population sizes. Although there have been no studies of the impact of these threats on crayfish, it is likely that the population of this species has been greatly reduced by severe habitat degradation. Furthermore, occasionally this species is used as a bait source by fishermen (C. Pedraza-Lara pers. comm. 2009).
|Conservation Actions:||There are no species-specific conservation measures in place for this species. Perez-Arteaga et al. (2002) identified Lake Chapala as a high priority to qualify for designation as a Ramsar Wetland of International Importance. Although not yet protected, the site is reported as likely to receive official designation as a natural area covered under the Ramsar Convention. Further research on the population status and impact of threats is needed.|
|Citation:||Alvarez, F., López-Mejía, M. & Pedraza Lara, C. 2010. Cambarellus prolixus. The IUCN Red List of Threatened Species 2010: e.T153714A4535728.Downloaded on 16 October 2018.|
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