1. Hydrothermal Vent Communities
How Life Originated?

2. Hydrothermal vent discovery-1977

3. Cold seawater sinks down through the crust.
O2 and K are removed from the seawater.
Ca, SO4, and Mg are removed from the fluid.
Na, Ca, and K from the crust enter the fluid.
Highest temperatures ( 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), …
Sea Water sinks through the crust and is filtered
Do Vents Affect the Entire Ocean? The world’s oceans contain many chemicals other than water and salt. Where do these chemicals come from? Rivers carry some of the chemicals into the ocean. Hydrothermal vents supply others. When seawater seeps down into the ocean crust and is heated by the magma, it undergoes lots of chemical reactions. When the fluid rises up through the seafloor, it carries many new chemicals with it, such as copper and zinc. These chemical reactions also remove chemicals from the seawater, such as oxygen and magnesium. Here is a look at some of the many chemical reactions that take place.
Cold seawater sinks down through cracks in the crust.
2. Oxygen and potassium are removed from the seawater.
3. Calcium, sulfate, and magnesium are removed from the fluid.
4. Sodium, calcium, and potassium from the surrounding crust enter the fluid.
5. The fluids have reached their highest temperatures. Copper, zinc, iron, and sulfur from the crust dissolve in the fluids.
6. Hot fluids carrying dissolved metals rise up through crust.
7. The hydrothermal fluids mix with cold, oxygen-rich seawater. Metals and sulfur combine to form black metal-sulfide minerals.
Basically cold seawater is converted to a very hot fluid rich in dissolved metals. Promotes robust chemistry  initial phase of life?

4. Robust and complex chemistry

5. 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.
2. The seawater continues to seep far below this point in the ocean crust. Energy radiating up from molten rock deep beneath the ocean floor raises the water's temperature to around °C. As the water heats up, it reacts with the rocks in the ocean crust. These chemical reactions change the water in the following way: All oxygen is removed. It becomes acidic. It picks up dissolved metals, including iron, copper and zinc. It picks up hydrogen sulfide.
3. Hot liquids are less dense and therefore more buoyant than cold liquids. So the hot hydrothermal fluids rise up through the ocean crust just as a hot-air balloon rises into the air. The 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. In white smokers, the hydrothermal fluids mix with seawater under the seafloor. Therefore, the black minerals form beneath the seafloor before the fluid exits the chimney. Other types of compounds, including silica, remain in the fluid. When the fluid exits the chimney, the silica precipitates out. Another chemical reaction creates a white mineral called anhydrite. Both of these minerals turn the fluids that exit the chimney white.

6. The beginning chemistry of life?

7. Hydrothermal Vent Distribution
Figure 1. Map of known hydrothermal vent biogeographic provinces and major mid-ocean ridges. Provinces: Pink, western Pacific; green, northeast Pacific; blue, East Pacific Rise; yellow, Azores; red, Mid-Atlantic Ridge; orange, Indian Ocean.
Pink, western Pacific; green, northeast Pacific; blue, East Pacific Rise;
yellow, Azores; red, Mid-Atlantic Ridge; orange, Indian Ocean

8. Hydrothermal energy source
H2S + O2  SO4 ++ H+ + ATP
Chemosynthetic (sulfur oxidizing)
Thermophilic Bacteria (up to 120oC)
Hot, anoxic, sulfide rich water mixes with Cold oxygenated water
Hydrothermal Vents as origin of Life?

9. Bacteria from 120oC

10. Vent biological communities
BACTERIA (Bacteria and Archea)
400 morphological invertebrate species
New species every 2 weeks during 25 years!
Evolutionary Origin
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

11. Cold Seeps
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

12. Invertebrate food sources
Food chain based on sulfur-oxidizing bacteria
Symbiosis with Bacteria
tube worms
Vent Mussels and vent clams
Ingestion of Bacteria
Grazers (gastropod limpets and snails)
Filter Feeders (vent shrimp, polychaete worms, amphipods, anemones)
Predators
Ventfish, octopus
Scavengers
Crabs

13. Tube worms

15. Vent Mussels (Bathymodiolus )

16.
Vent Clams
(Calyptogena)

17. Vent Shrimp (Bresiliidae)

18. Alvinellid worms

19. Vent limpets

20. Vent Crabs www.divediscover.whoi.edu/i
Vent Crabs

21. Ventfish (Thermarces cerberus)

22. Light organs in vent organisms

23. Periferic filter feeders

24. Sea floor Spreading opens new vent areas over geological time

25. Depends on ambient temperature
Chemical Reactions
Depends on ambient temperature
A beehive of activity. Microbial niches in serpentinization-
influenced environments at the
Lost City hydrothermal field. (A) Exothermic
serpentinization reactions within the subsurface
produce fluids of high pH enriched in
methane and hydrogen, as well as some hydrocarbons.
(B) Environments within the warm
interior of carbonate chimneys in contact with
end-member hydrothermal fluids host biofilms
of Methanosarcina-like archaea (green circles).
These organisms may play a dominant role in
methane production and methane oxidation
within the diverse environments present in the
chimneys. Bacterial communities within these
biotopes are related to the Firmicutes (purple
rodlike cells). These organisms may be important
for sulfate reduction at high temperature
and high pH. (C) Moderate-temperature (40° to
70°C) endolithic environments with areas of
sustained mixing of hydrothermal fluids and
seawater support a diverse microbial community
containing Methanosarcina-like archaea,
ANME-1 (a methane-oxidizing phylotype; blue
rectangular cells), and bacteria that include

26. Hydrothermal Vent Communites
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
Biomass
Up to 30 kg/m2
1000 x greater than
typical biomass
observed on
deep-sea floor
Geol 104/BioES 154

27. 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.
Geol 104/BioES 154