1. Microbial Metabolisms Influence Carbonate Precipitation in a Laminated Microbial Mat
Dylan Wilmeth, Sharon Grim, Megan Krusor,
Hope Johnson, Will Berelson, Blake Stamps,
Olivia Piazza, Bradley Stevenson,
Frank Corsetti, John Spear

3. Carbonates in Microbial Mats

4. Carbonates in Microbial Mats
Growth rates of inorganic vs. organic carbon
Biogenic vs. abiogenic carbonate precipitation

5. Hypothesis: Autotrophic Growth
Inorganic
Carbon
Growth
Organic Carbon Growth

6. Hypothesis: Autotrophic Growth
Inorganic
Carbon
Growth
Organic Carbon Growth

7. Hypothesis: Autotrophic Growth
Inorganic
Carbon
Growth
Organic Carbon Growth

8. Data
Inorganic
Carbon
Growth
Organic Carbon Growth

9. Field Location: Little Hot Creek, CA

11. See how it slows down and flattens out?
1 m

12. Microbial Mats
1 m

13. Mat Carbonate
5 cm
200 μm

14. Methods A B C D
5 cm

15. Organic Carbon
HCO3- spike
δ13C = ‰
13C
13C
13C

16. Organic Carbon
Incubation: 40° C
12 hrs light, 12 hrs dark
13C
13C
13C

17. Organic Carbon
Incubation: 40° C
12 hrs light, 12 hrs dark
13C
13C
13C
13C
13C
13C
13C
13C
13C

18. Fraction of Growth / day
Organic Carbon
Fraction of Growth / day
Example:
13C
13C
13C
13C
13C
Original
Carbon
13C
13C
New Carbon
13C :
= 0.5
13C

19. Results – Organic Growth / Day
Organic Carbon Growth / day
(fraction of original Corg)

20. Mat Layers
A B C D A B C D

21. Organic Carbon Growth / day
Inorganic
Carbon
Growth / day
(fraction of original Cinorg) C D B A
Organic Carbon Growth / day
(fraction of original Corg)

22. Organic Carbon Growth / day
Inorganic
Carbon
Growth / day
(fraction of original Cinorg) A
Organic Carbon Growth / day
(fraction of original Corg)

23. Biogenicity of Carbonate Precipitation

24. Biogenicity of Carbonate Precipitation

25. Results: Abiogenic
δ13C Inorganic Carbon
(‰)
Control

26. Results: Abiogenic
δ13C Inorganic Carbon
(‰)
Control

27. Results: Biogenic
δ13C Inorganic Carbon
(‰)
Control

28. Results: Biogenic
δ13C Inorganic Carbon
(‰)
Control

29. Carbonate Precipitation
At Little Hot Creek:
Autotrophic carbon production does not foster carbonate precipitation
Biogenic and abiogenic processes precipitate carbonate within mats

30. Future Work Pinpointing Biogenic and Abiogenic Processes
Autotrophic vs. heterotrophic influence on precipitation
Precipitation within poisoned mats
Continuing similar work on other mats

31. International Geobiology Course 2015
Thank You!
International Geobiology Course 2015
Lead Instructors: Frank Corsetti, John Spear
Team Lasagna: Will Berelson, Hope Johnson, Brad Stevenson, Blake Stamps, Steve Karl
Field Lasagna Researchers: Emma Bertran, James Bradley, Gabriela Libanori, Olivia Piazza, Nick Rollins, Danielle Santiago, Lennart van Maldegem
US Forest Service
All of our peers and instructors who gave us great feedback!
USC Wrigley Center for Environmental Studies
Agouron Institute