Microbial Diversity in the Subsurface - Kane Caves Project
University of Texas at Austin


Microbial Mats

Microbial mats are found as thick filamentous mats (or "plumes") in the stream coming from spring outlets. White mats occur in three main places in the cave, at the Fissure Spring, Upper Spring outflow channel, and within the Lower Spring and outflow. 

Large populations of snails graze on the mats, and collembola (spring-tails), identified as Folsomia candida by Dr. Ken Christiansen (Grinnell College, Iowa), were found in the sediment adjacent to the Fissure Spring mats. According to Dr. Christiansen, F. candida is an opportunistic species rarely found in the soil, but common to disturbed and artificial places such as greenhouses, wells, potted flowers, and in cave sites  not occupied by cave-adapted species. The snails are Physa spelunca, identified by Dr. John Holsinger (Old Dominion, Virginia), and are cave-adapted. 

Visit the Kane Caves Macroinvertebrate Page

Black and red microbial mats are also found in the cave. Black mats are closest to the spring orifices, red mats are found away from the springs, and the boundary between these mats is quite dramatic. SEM examination of the black mats reveals the presence of Fe-S framboid structures, and examination of the red mats shows the occurrence of iron-oxidizing bacterial sheaths and stalks. 

Slimy biofilms on subaerially-exposed cave-walls coat gypsum and elemental sulfur deposits. The gypsum covers the limestone hostrock and can reach several 10's of cm in thickness (average thickness ~5 cm). Acid droplets on these wall surfaces and biofilms have an average pH of 1.75 (n=40), and yet are 'teeming with life!' There are even tiny collembola on the cave-walls, presumably grazing upon the biofilms, but they have not been identified yet.


White filamentous microbial mats located at 
"Fissure Spring" in Lower Kane Cave, Wyoming.

Closeup of P. spelunca on a chert cobble, 
located within the Upper Spring white mats. 
The average length of the snails is 43 mm (n=117). 

                   Details found on the Macroinvertebrate Webpage
                   maintained by M.L.Porter (Brigham Young University).

Diversity of Microbial Communities

These microbial mats  found throughout Lower Kane Cave each have a distinct and complex microbial community. So far, we have identified the various metabolic groups.

White Mats   
Composed of: sulfur-oxidizing bacteria, sulfate-reducing bacteria, fermenters, methanogens, aerobic heterotrophs

Black Mats    
Composed of: fermenters, aerobic heterotrophs

Red Mats 
Composed of: sulfur-oxidizing bacteria, sulfate-reducing bacteria, fermenters, aerobic heterotrophs

Cave-Wall Biofilms    
Composed of: sulfur-oxidizing bacteria

 


Red mats located in side channel, Lower Kane Cave, 
Wyoming. Water drains from beneath
gypsum mounds, 
and has entrenched the microbial mats . 
A pen is in the lower left corner for scale.

 

Phase contrast photomicrograph of filamentous 
white mats from the Upper Spring.

 


Last updated: 07/13/09. Images, maps, and other original material copyrighted by Annette Summers Engel, Baton Rouge, LA, USA.