MICROBIAL SUCCESSION IN A TAR SEEP DECOMPOSITION ENVIRONMENT

Natural tar seeps are the source of millions of fossils from animals that became entrapped, died and were decomposed over the millennia, as exemplified by the La Brea Tar Seeps in Los Angeles. The microbial communities responsible for the anaerobic decomposition of these entrapped animals has not been known. However, microbial communities likely play a role in the rapid time to skeletonization of animal components submerged in tar. We hypothesized that high-energy animal tissue would support fast-growing taxa and support lower microbial diversity and that microbial succession across different locations in the tar environment would resemble known patterns of microbial decomposition in similar habits. We sampled different locations in a tar seep and also bobcat limbs that were experimentally submerged in the seep and left to decay until skeletonization. Microbial communities were characterized using 16S rDNA sequencing of the V4 region. We found that decay communities had lower diversity than tar environment communities and that microbial succession proceeded similarly to that in analogous habitats. The addition of animal tissue into this tar seep may stimulate rapid microbial community succession and likely influenced the rate of decomposition of this tissue. Future experiments are required to understand the role of microbial succession in determining the rate of decomposition and time to skeletonization in tar environments.