chemosynthesis: methane seeps and their fauna

Chemosynthesis:Methane Seeps and their Fauna.

byKevin Townsley and Bob Russman

A Mars analog for life?

IntroductionExploration for oceanic hydrocarbon deposits is driven primarily by oil interests looking for new sources of fuel and by scientists seeking a better understanding of methane flux between source, sink, and the atmosphere. ([1], [6], [11], [12])

IntroductionMany scientists link hydrocarbon sources in carbonate deposits to interacting chemosynthetic and biogenic processes occurring in these seemingly toxic environments. One possible reaction pathway involves “reverse methanogenesis”: ([9], [10] )

IntroductionExobiology goals for Mars: Determine whether life presently exists, or more likely existed, on Mars. ([3])

1.Define the nature of early martian environments and understand differences from early Earth environments.

2.Determine the history of the biogenic elements (Carbon, Hydrogen, Nitrogen, Oxygen, Sulphur, Phosphorus) on Mars and the organic chemistry there (biologic or abiologic in origin).

IntroductionSeveral past, current, and planned, unmanned Mars missions are working to achieve these lofty goals.

Orbital Missions: Mars Global Surveyor (1996-2006) Mars Odyssey (ESA) (2001 - present) Mars Reconnaissance Orbiter (2005 - present) Mars Atmosphere and Volatile Evolution (2014)

Surface Missions: Mars Exploration Rovers (2004 – present) Mars Phoenix Lander (2007) Mars Science Lab (2012 – present) Mars Sample Return (2020’s???)

BackgroundSeveral independent studies on methane seeps focus on both living communities and fossil/paleo assemblages occurring globally in active and passive continental margins.

BackgroundGas hydrate precipitates and authigenic carbonate can form many structures: ([1], [9])

Mounds: buried hydrates

Platforms: authogenic buildups

Chimneys: column relics

Mud Volcanoes: Flow features

Mud Diapir: elongate ridges

Pockmarks: Craters

Fissures: hydrate intrusions

Bioherms: Coral like features

Do any of these features stand out in the image?Anaglyph photo: NASA/JPL/University of Arizona/Russman

BackgroundBiogeographic analysis show increases in seep fauna and decreases in background and predator taxa with increased depth. [7]

Background“Typical” methane seep fauna include a variety of species from these phyla:

Molluscs Bivalves: Caspiconcha and Calyptogena Gastropods: Serridonta and Hoikkadoconcha

Sulfate Oxidizing Proto-Bacteria Beggiatoa Desulfococcus / Desulfosarcina

Eutamazoans Pognophoran Tubeworms

Archea Methanogens Bacterial Mats

[6], [7], [8], [9], [10]

BackgroundThe Mollusca share a symbiotic relationships with sulfate oxidizing bacteria and are considered endemic to New Zealand methane seep environments:[8]

The large bivalve Caspiconcha (A) the lucinid bivalve Nipponothracia (B) and all small limpets and skeneiform gastropods (C)

A B C

BackgroundThe Archea methanogens and Eutamozoan tubeworms dominate areas with the highest CH4 concentrations. [5][6][9][10]

BackgroundHydrates precipitate from dissolution as a function of temperature. Cooling occurs with distance away from the warmer rising gas column.

Cores from the Hakon Mosby mud volcano indicate that hydrates form concentrically around the crater normal to flow. Methanotrophic bacterial mats form in the center and are surrounded by sulphate oxidizing bacteria.

BackgroundThe Hakon Mosby mud volcanoes are exemplary of the pattern displayed by bacterial seep communities in response to the hydrates position within the flow field. The absence of bivalves is due to the short time this seep has been active.

BackgroundThe implications of methanogenic microbial buildup of carbonates in seep environments are important for Mars exploration. [11]

(Mumma, 2009) NASA/JPL/University of Arizona/Russman

BackgroundSpectral analysis of Nili Fossae confirm the presence of carbonates. [2], [13]

USGS Lab Spectra CRISM NF Spectra

BackgroundThe morphology of the Nili Fossae region attest to a complex history of sedimentation and erosion preceded by impact event tectonics. Presence of phyllosilicate clays and hydrous minerals suggest deposition in an aqueous environment. [2], [13]

Background

Problem

Problem1. How do we differentiate between non-symbiotic and

symbiotic organisms?

2. How do they link carbonate deposits to methanotrophic microbial activity?

3. How do we use spectroscopy to identify minerals?

4. How can we directly test carbonate deposits on Mars for biologic or abiologic origin?

Problem

[5]

Organisms uptake carbon during the extent of its life. After death carbon decays from 14C parent ions to 12C and 13C daughters.

Also 15C from fatty acids is used as a biomarker to identify sedimentary origins.

Problem1. How do we differentiate between non-symbiotic and symbiotic organisms at methane seep sites?

Chemosynthetic marine organisms ultimately yield higher total -13C ppm than photosynthetic organisms.

Photosynthetic marine organisms ultimately yield higher total -12C ppm than chemosynthetic organisms.

Chemosynthetic marine organisms must be symbiotic, as they rely on the methanogens.

ProblemCalcite, Aragonite, and Dolomite each have a unique spectral signature, but the intermixing of sediments obscure those signals in the process.

ProblemHowever, spectral patterns may emerge at smaller scales. The similar features between the Nili Fossae potential mud flow and Hakon Mosby mud volcano, and the relationship between biota and hydrates there, gave me an idea.

ProblemWhen we mapped the spectral signatures a pattern did emerge with concentrations of bright material (magenta) dispersed away from the crater center in a manner that is similar to the hydrates described at Hakon Mosby.

Certainly interesting but hardly enough to suggest life on Mars…

Conclusion

Conclusion

ReferencesWorks CitedBrother, L L. "Evidence for extensive methane venting on the southeastern U.S. Atlantic margin." Geology, 2013: 807 - 810.Brown, A J, and etal. "Hydrothermal formation of Clay-Carbonate alteration assemblages in the Nili Fossae." Earth and Planetary Science Letters 297, 2010: 174-182.Cabrol, Natalie. Cenetr for Mars Exploration/Exobiology: The Search for Life on Mars. 2010. http://cmex.ihmc.us/CMEX/data/SiteCat/sitecat2/exobiolo.htm (accessed November 22, 2013).Cloutis, Edward A, Stephen E Grasby, William M Last, Richard Leveille, Gordon R Osinski, and Barbara L Sherriff. "Spectral reflectance properties of carbonates from terrestrial analogue environments: Implications for Mars." Planetary and Space Science, 2010: 522-537.Cordes, Erik E, Michael A Arthur, Shae Katriona , Rolf S Arvidson, and Charles R Fisher. "Modeling the Mutualistic Interactions between Tubeworms and Microbial Consortia." PLOS Biology, 2005: 497-506.Ding, Haibing, and David L Valentine. "Methanotrophic bacteria occupy benthic microbial mats in shallow marine hydrocarbon seeps. Coal Oil Point, California." Journal of Geophysical Research, 2008.Kiel, Steffen. "On the potential generality of depth-related ecologic seep structure in cold-seep communities: Evidence from cenozoic and Mesozoic examples." Paleogeography, Paleoclimatology, Paleoecology, 2010: 245-257.Kiel, Steffen, Daniel Birgel, Kathleen A Campbell, James S Crampton, Poul Schioler, and Jorn Peckmann. "Cretaceous methane-seep deposits from New Zealand and their fauna." Paleogeography, Paleoclimatology, Paleoecology, 2013: http://dx.doi.org/10.1016/j.palaeo.2012.10.033.Levin, Lisa A. "Ecology of Cold Seep Sediments: Interactions of Fauna with Flow. Chemistry and Microbes." Oceanography and Biology: An Annual Review, 2005: 1-46.Milkov, Alexei V, et al. "Geological, geochemical, and microbial processes at the hydrate-bearing Hakon Mosby mud volcano,: a review." Chemical Geology, 2004: 347-366.Mumma, Michael J, et al. "Strong Release of Methane on Mars in Northern Summer 2003." Science, February 20, 2009: 1041-1045.Smith, Thomas. "Gas Hydrates- Not So Unconventinal." GeoEXPRO, 2009: 26-28.Wray, James J, and Bethany L Ehlmann. "Geology of possible Martian methane source regions." Planetary and Space Science, 2011: 196-202.

Potential Exam Questions

Are methane seeps useful in biogeographic correlation?

How do methane seeps exhibit endemism?

Is there evidence at methane seeps to suggest life on Mars?