Cueva de El Pachón, San Luis Potosí, Mexico

Environment

Environment

Untouched

Surrounding area

Cueva de El Pachón is located in the Sierra de El Abra karst region of San Luis Potosí, northeastern Mexico, within the Pánuco River Basin. The cave lies beneath tropical semi-evergreen forests growing on limestone hills. Rainwater infiltrates the porous karst landscape, feeding underground streams and pools with clear, mineral-rich water. The cave maintains a stable environment throughout the year, with high humidity, constant temperatures, and complete darkness beyond the entrance. Organic matter entering from the surface provides the primary source of nutrients for the subterranean ecosystem.

Underwater landscape

The habitat consists of clear underground pools connected by slow-flowing passages over limestone bedrock. The substrate is composed of limestone rocks, gravel, and fine calcareous sand, with very little suspended sediment. Aquatic vegetation is absent due to the lack of sunlight. The Blind Cave Tetra (Astyanax mexicanus) is the dominant fish species, accompanied by cave-adapted invertebrates such as freshwater shrimp. Rock crevices and submerged cavities provide shelter and potential breeding sites.

Fish:

• Astyanax mexicanus (Characidae) – Cave morph (El Pachón population)

Crustaceans:

• Typhlatya mitchelli (Atyidae)
• Macrobrachium cf. acanthochirus (Palaemonidae)

Threats to ecology

Although relatively isolated, the cave ecosystem is vulnerable to groundwater pollution, excessive groundwater extraction, quarrying, land-use changes above the cave, and increasing tourism. Because cave species have evolved in highly stable environments, even small changes in water quality or hydrology can have significant ecological consequences. The conservation of the surrounding karst landscape is essential for protecting this unique subterranean ecosystem.

Riparian zone

Trees near the aquatic habitat

Many - Ficus cotinifolia (Moraceae)

Trees near the aquatic habitat

Many - Lysiloma divaricatum (Fabaceae)

Trees near the aquatic habitat

Few - Bursera simaruba (Burseraceae)

Bibliography

• → BMC Evolutionary Biology - The complex origin of Astyanax cavefish by Gross, J.B.
  
• → Annual Review of Genetics - Regressive Evolution in Astyanax Cavefish by Jeffery, W.R.
  
• → Association for Mexican Cave Studies Bulletin - The Astyanax Caves of Mexico by Elliott, W.R.
  

Sitography

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