Yucatán Peninsula, Mexico
The Yucatán Peninsula aquifer is an extensive karst groundwater system in southeastern Mexico. Its hydrogeology is characterized by highly permeable limestone, which enables the rapid infiltration of precipitation directly into subsurface conduits, caves, and cenotes (sinkholes), while also allowing marine water to infiltrate into the Peninsula.
The biotic diversity within the Yucatán aquifer comprises 67 obligate groundwater (stygobitic) species which are highly endemic, and span across several phyla including Arthropoda, Gastropoda, Echinodermata, and Chordata. Among these, crustaceans are the most diverse and common macrofaunal component. Microbial assemblages in these caves and conduits are similarly diverse, yet await further investigation. They are expected to be an important complement to the foundational trophic layer in these dark, nutrient-limited systems, that also get sporadic nutrients from the surface infiltration.
This aquifer is critical for water supply: many communities rely on it for drinking water and local agriculture. The cenotes — natural sinkholes that expose the aquifer to the surface — also support a tourism industry that draws visitors for swimming and cave diving. However, the system is under anthropogenic stress. Nutrient contamination (e.g., nitrates) and emerging pollutants such as pharmaceuticals have been detected in groundwater, linked especially to domestic sewage, tourism, and urban development. More recently, microplastic particles have also been found in the karst aquifer, raising new concerns about water quality. Protecting this groundwater resource is vital not only for human water security but also for preserving its unique subterranean ecosystems, whose endemic species can act as sensitive biological indicators of aquifer health.
Words by Efrain Chavez
Photos by Kay Vilchis, Liz Borda & Efrain Chavez