Anchialine pools and cenotes

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Introduction

Amazing photo of Yax Mul cenote on the Yucatan Peninsula, Mexico.

Anchialine pools, also known as Cenotes in the Yucatan Peninsula region, are subterranean bodies of water that have a connection to the surface. Anchialine pools are circular and cliffed sinkholes that contain watertable lakes. They are filled with brackish water. hThey contain large passage ways which make them desirable for cave explorations. They are very common globally, with the most popular located in the Hawaiian Islands and the Yucatan Peninsula, Mexico.

Anchialine pools are home to different types of grazers. Thick and intricate microbial mats also form in these areas due to nutrients provided by hydrothermal inputs. The microbes in the microbial mats undergo anaerobic respiration. Microbial processes that occur here include: methanogenesis, sulfur reduction, and anaerobic ammonia oxidation.

Physical environment

Vegetation

There are many species that are endemic to anchialine pools including flora, fauna, and microbial communities. Characteristic heterogeneous vegetation, including tall evergreen trees like Ficus species, surrounds the opening of the pools. Removal of vegetation by large herbivores is threatening the ecosystems that reside in the anchialine pools.

Formation

Anchialine pools are formed by the dissolution of limestone by carbonic acid in karst landforms. Underlying these landforms is calcerous rock. As the rock breaks off and falls into the pool, it is further dissolved. In the Hawaiian Islands, these pools occur in highly porous substrates like recent lavas or limestone that are near the ocean.

Hydrology

Anchialine pools experience tidal fluctations and lack surface connections that are near the ocean. They contain very clear water and large channels. They are filled with brackish water. They experience a salinity gradient throughout the water column. Salinity decreases as depth increases.

Topography

Anchialine pools are common on coastal karst plains with low topography.

Animal Community

Anchialine pools serve as the main source of water for humans and animals in regions like the Yucatan Peninsula.

Microbial communities

What kind of microbes do we typically find in this environment? Or associated with important processes in this environment? Describe key groups of microbes that we find in this environment, and any special adaptations they may have evolved to survive in this environment. List examples of specific microbes that represent key groups or are associated with important processes found in this environment. Link to other MicrobeWiki pages where possible.

Are there important biological interactions that are important in this environment? Do these interactions influence microbial populations and their activities? How do these interactions influence other organisms? Describe biological interactions that might take place in this environment, using as many sections/subsections as you require. Look at other topics available in MicrobeWiki. Create links where relevant.

Methanogens

Sulfur reducing bacteria

Microbial processes

What microbial processes define this environment? Describe microbial processes that are important in this habitat, adding sections/subsections as needed. Look at other topics in MicrobeWiki. Are some of these processes already described? Create links where relevant.

Anaerobic respiration

Anaerobic respiration occurs when microbes use other terminal electron acceptors other than oxygen. In environments, like anchialine pools and cenotes, microbes use terminal electron acceptors like sulfate (SO₄^-2), nitrate (NO₃^-), sulfur (S), and carbon dioxide (CO₂). This type of respiration occurs in the absence of oxygen. Although these terminal electron acceptors produce energy, they release less energy than oxygen. Therefore, anaerobic respiration produces less energy than aerobic respiration.