Transcript Biosignatures and Bioindicators

Biosignatures and
Bioindicators
Clearing the ambiguous Meanings in
Astrobiology and in other scientific Areas
H. Spuller, June, 26th 2013
Bioindicators
General Definition
A Bio-indicator is an organism or a
biological response:
Biological indicators are species that
can be used to monitor the health of
an environment or ecosystem. They
are any biological species or group
of species whose function,
population, or status can reveal
what degree of ecosystem or
environmental integrity is present.
e.g. Caddisfly (order Trichoptera), a macroinvertebrate used as an indicator
of water quality.
(http://en.wikipedia.org/wiki/Biomarker, missing citations; vista June 26th 2013)
This definition is obvously not usable for exobiology
Macronvertebrate: bestia sine columna vertebralis satis apparet esse
Bio-indicators in Exobiology
Bio-indicators are indicative of biological
processes but can also be produced
abiotically insignificant quantities.
Therefore it is essential o model and
understand the abiotic sources of
biomarkers better, so that we can
identify when it might constitute a “false
positive” for life detection, when abiotic
sources could produce high quantities of
a species we understand as a biomarker
on Earth.
(Kaltenegger, Selsis 2008; ESA White Paper)
Biomarker
Biomarker (or biosignature)
is used in exobiology to
mean detectable species, or
set of species, whose presence at significant abundance strongly suggests a
biological origin. This is for
instance the case for
the couple CH4+O2 or for
O3, N2O, and recently CH3Cl
(Kaltenegger, Selsis 2008; ESA White Paper)
CH4
H2O
O2
CO2 