Sulfur Cave Microbial Ecology---Cueva de Villa Luz

Team

Diana E. Northup University of New Mexico	Penelope J. Boston Complex Systems Research
Michael N. Spilde University of New Mexico	Kathleen H. Lavoie SUNY Plattsburgh
Carlos Alberto Cordero Martinez Kolem Ja, Tabasco, Mexico	Alejandra Alvarada Zink Universum Science Museum
Louise Hose National Cave and Karst Research Institute

Summary

Cueva de Villa Luz, located in southern Mexico in the state of Tabasco in the Cretaceous limestone, is a moderately size cave (2 kilometers of passage) with numerous skylights. What makes it so different is the nasty smell of rotten-eggs from hydrogen sulfide and the passages teeming with life based on the oxidation of this hydrogen sulfide. Spiders and their egg cases hang on webs located right next to walls that are dissolving and whose pH is 0.0 to 0.5. A team of biologists and geologists joined Jim Pisarowicz, who learned of the cave from the local people, and Louise Hose, in exploring this fantastic cave in January of 1998.

Interesting Findings

Down this passage is some red goo which we sampled. Red goo, a complex clay breakdown product, ranges from pH 3.9 to pH 2.5. Clusters of bacterial cells live in this material. How are they making their living and what is the source of the concentrated rare earth elements found in the goo?

More about red goo

In total darkness are rocks covered with a green slime. In this case, there were microbial filaments in the stream nearby. Bacteria-sized cells are present in abundance. Midges cluster on these rocks in great numbers and may be grazing on the bacteria.

More about green slime

Snottites are slimy, dripping stalactites made of goo, that contain bacteria in abundance and beautiful microscopic gypsum crystal formations. Both exist at the same time in an environment whose pH is 0.5! Biovermiculations are worm-shaped deposits on the walls, which contain numerous bacteria.

More about snottites and biovermiculations

Jim Pisarowicz has a bunch of general information about Cueva de Villa Luz.

Preliminary Report on the Biology of Cueva de Villa Luz, Tabasco, Mexico

Kathy Lavoie (State University of New York, Plattsburgh NY, USA),
Diana Northup (University of New Mexico, Albuquerque, NM, USA),
Penny Boston (New Mexico Tech, Socorro, NM, USA),
Carlos Blanco-Montero (Escuela Superior de Agricultura del Valle del Fuerte).

We participated in the January, 1998 Expedition to Cueva de Villa Luz in Tapihualapa, Tabasco, Mexico, organized by Jim Pisarowicz and Louise Hose. We present a preliminary overview of the biology of this interesting cave. Identifications of many species are still pending. We were initially attracted by the prospects of investigating a sulfur-based ecosystem, but the actual situation is much more complicated. Much of the cave is a stream passage, milky-white with sulfur. Many passages in the cave have very high levels of H2S, varying during this expedition from 0 to 57-127 ppm. Most passages were above 10 ppm. The pH of the environment was generally more acidic than typically found in a limestone cave. Exceptionally low pHs were associated with "snottites" or microbial veils (pH 0.3-0.7), and in one area we identified a deposit of bat guano mixed with gypsum paste which had a pH of 0.0. Sulfate-reducing bacteria were present in very high numbers (105-106 +) in all sediments. Coliform bacteria survived in the main stream passage, but were not detected in springs entering the cave. Microbial involvement is evident in the formation of white filaments in the cave stream and in microbial veils suspended from gypsum, possibly in association with webs of spiders or fungus gnats. There are also significant organic inputs through numerous skylights and from bat guano and other animals. Previous studies identified four types of phyllostomid bats in the caves. We also observed free-tail bats, probably Tadarida brasiliensis, as well as numerous vampire bats. Bats roosted in good air sections of passages, but flew freely though bad air passages. The most abundant organisms are the midges, Tendipes fulvipilus, which are the main prey for the molly, Poecilia sphaenops, which consumes both the aquatic larvae and adults. The fish are in turn preyed upon by a diving hemipterin (not identified). Both fish and midges are present in very high densities of hundreds to thousands of individuals in relatively small areas. The fish range from a cave-adapted form with reduced eyes and no pigmentation to a dark surface stream form with apparent intergradation between these two extremes. There was a very high density of predatory invertebrates throughout the cave, particularly spiders, fungus gnat larvae, and amblypygids. We found little evidence for terrestrial troglobites, with the possible exception of a spider and nematodes found in highly acidic vermiculations. We noted a surprising general lack of beetles, cave crickets and collembola. Studies to characterize the species collected are on-going, including molecular phylogenetic studies of DNA sequences from microbial communities in both terrestrial and aquatic environments. At the end of the expedition new passages were discovered in the cave. The new areas are typical limestone cave passages with good air; future studies of the types, distributions and abundance of animals in this part of the cave compared with the sulfur passages will be extremely interesting.