A: A photograph of the location and basic setup of the microcosm experiment. B-D: Overhead views of the microcosms on day 10 of the experiment. B: The abiotic microcosm showing an extensive crust of nesquehonite on the bottom of the container. C: The unamended mat and D: the amended eutrophic microcosms do not contain a nesquehonite crust. Also the mats in the eutrophic system are considerably greener than the unamended system indicating new microbial growth.