Download Precambrian Marine Microbes

Objectives:
1. Know the dates of the Precambrian time
period
2. Understand the ecological role of the primary
producers of the Precambrian.
3. Understand how the marine organisms of the
Precambrian changed the physical aspects of
our planet.
Precambrian
• Spans from the formation of the earth 4.6 bya
to 542 Mya.
• The Precambrian accounts for 88% of geologic
time
• Precambrian fossil record is poor because
many of the rocks have been metamorphosed,
and the organisms are soft bodied.
Archaea Bacteria
• Archaebacteria emerged at least 3.5 billion
years ago and are the oldest life forms.
• Many live in extreme environments.
Examples of Archea bacteria
• Halophiles: Live in extremely salty
environments
• Thermophiles: Live in extreme heat
• Methanogens: Obtain energy through the
metabolism of methane gas
Stromatalites
• The oldest rock on earth (3.5 bya), located in
australia include fossils of stromatalites.
• Mats of blue-green algae (cyanobacteria)
formed in shallow water by the trapping, and
cementation of sedimentary grains.
• The represent some of the most ancient forms
of life.
A New Atmosphere
• cyanobacteria oxygen as a waste gas and so
helped establish an aerobic ecosystem
• They helped establish a stable oxygen rich
atmosphere.
• These new atmospheric conditions calmed
the weather so that the extremes were less
severe.
Heterotrophic Bacteria
• “hetero”= different
• “trophic” = eating
• Heterotrophic = Decomposers which use
available organic matter to obtain energy.
Biological Pump
• Organic Carbon from dead organisms is
transported by sinking particulate, some reaching
the ocean floor.
• Through bacterial respiration by decomposers,
carbon is returned to the ocean as dissolved CO2
(Carbon dioxide) and Nitrogen is returned as N2
(nitrogen gas)
• Decomposition processes are generally slower
than Synthesis processes, which results in
nutrients being transported from the ocean
surface to the ocean floor.
The Carbon and Nitrogen Cycle
• Carbon Cycle: the movement of carbon between
the abiotic (non-living) and biotic systems (living).
• Nitrogen fixation: The process in which bacteria
converts N2 gas into NH3
• Nitrification: Microbes convert NH3 into NO2 and
NO3, that primary producers (cyanobacteria) can
use.
• Nitrogen is required to form amino acids and
nucleotides.
• Nitrogen is often a limiting nutrient in
ecosystems.