Hydrothermal Vent Communities
•How Life Originated?
Hydrothermal vent discovery-1977
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•Basically cold seawater is converted to a very
hot fluid rich in dissolved metals. Promotes
robust chemistry  initial phase of life?
Cold seawater sinks down
through the crust.
O2 and K are removed from
the seawater.
Ca, SO4, and Mg are removed
thesinks
fluid.
•from
Sea Water
through the crust
Na,is Ca,
and K from the crust
and
filtered
enter the fluid.
Highest temperatures (350400 oC), Cu, Zn, Fe, and H2S
from the crust dissolve in the
fluids.
Hot & acidic fluids with
dissolved metals rise up
through crust.
The hydrothermal fluids mix
with cold, O2-rich seawater.
Metals and sulfur combine to
form metal-sulfide minerals:
MnO2, FeO(OH), …
•Robust and
complex
chemistry
www.pmel.noaa.gov/
Black & White smokers
2. As the water heats up, it reacts with
the rocks in the ocean crust
All oxygen is removed.; It becomes acidic.
It picks up dissolved metals, including iron,
copper and zinc.
It picks up hydrogen sulfide.
•3.The hot
rising fluids carry the dissolved
metals and hydrogen sulfide with them.
•4. The hydrothermal
fluids exit the
chimney and mix with the cold seawater.
The metals carried up in the fluids combine
with sulfur to form black minerals called
metal sulfides. These tiny mineral particles
give the hydrothermal fluid the appearance
of smoke.
Many factors trigger this reaction. One
factor is the cold temperature of the
seawater. A second equally important factor
is the presence of oxygen in the seawater.
Without oxygen, the minerals would never
form.
•The beginning chemistry of life?
Hydrothermal Vent Distribution
Pink, western Pacific; green, northeast Pacific; blue, East Pacific Rise;
yellow, Azores; red, Mid-Atlantic Ridge; orange, Indian Ocean
Hydrothermal energy source
H2S + O2  SO4 ++ H+ + ATP
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Chemosynthetic (sulfur oxidizing)
Thermophilic Bacteria (up to 120oC)
Hot, anoxic, sulfide rich water mixes
with Cold oxygenated water
Hydrothermal Vents as origin of Life?
Bacteria
from 120oC
http://mollie.berkeley.edu/~volkman/
Vent biological communities
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BACTERIA (Bacteria and Archea)
400 morphological invertebrate species
• New species every 2 weeks during 25 years!
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Evolutionary Origin
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Derived from surrounding Deep Sea
Derived from Shallow Water species
Many evolutionary radiations at species level
Many vent taxa originated at other organically
enriched environments (cold seeps and whale
bones)
Vents as stable refugia from Global
extinctions
Cold Seeps
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CH4 + O2  CO2 + H20 +ATP
CH4  CH3- + H+ +ATP
H2S + O2  SO4 ++ H+ + ATP
Hydrocarbon reservoirs
“methane bubbling”
Continental shelves and Trenches
200 invertebrate species
•ATP is used as an energy carrier for
cells; natural synthesis
Invertebrate food sources
Food chain based on sulfur-oxidizing bacteria
 Symbiosis with Bacteria
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Ingestion of Bacteria
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Grazers (gastropod limpets and snails)
Filter Feeders (vent shrimp, polychaete worms, amphipods,
anemones)
Predators
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tube worms
Vent Mussels and vent clams
Ventfish, octopus
Scavengers
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Crabs
Tube worms
http://web.uvic.ca/%7Everenat/364-13.jpg
Vent Mussels (Bathymodiolus )
www.divediscover.whoi.edu/i
www.divediscover.whoi.edu/i
Vent Clams
(Calyptogena)
Vent Shrimp (Bresiliidae)
www.ifremer.fr/
Alvinellid worms
Vent limpets
http://web.uvic.ca/~abates/
www.divediscover.whoi.edu/i
www.senckenberg.uni-frankfurt.de/
Vent Crabs
Ventfish (Thermarces cerberus)
Light organs in vent organisms
www.deepsea.com/
Periferic filter feeders
Sea floor Spreading opens new vent
areas over geological time
www.pmel.noaa.gov/vents/PlumeStudies
Chemical Reactions
•Depends on
ambient
temperature
Hydrothermal Vent Communites
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25 years of exploration have revealed:
A new phylum
 At least 20 new families
 Over 90 new genera
 Over 300 new species
 Over 250 new strains of
free-living bacteria
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Biomass
Up to 30 kg/m2
 1000 x greater than
typical biomass
observed on
deep-sea floor
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Geol 104/BioES 154
Hydrothermal Vent Macrofauna:
Environmental Constraints on Life
Cycles and Reproduction
Suitable vent environments for these
organisms are rare.
� Individual vents have short life-spans.
� Volcanic eruptions and earthquakes pose
further hazards.
�These conditions favor rapid growth rates,
continuous reproduction, and high
fecundity.
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Geol 104/BioES 154