Hydrothermal Vent Communities How Life Originated Hydrothermal vent

Hydrothermal Vent Communities • How Life Originated?

Hydrothermal vent discovery-1977

• • 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. O 2 and K are removed from the seawater. Ca, SO 4, and Mg are removed from the fluid. • Sea Water sinks through the crust Na, is Ca, and K from the crust and filtered enter the fluid. Highest temperatures (350400 o. C), Cu, Zn, Fe, and H 2 S from the crust dissolve in the fluids. Hot & acidic fluids with dissolved metals rise up through crust. The hydrothermal fluids mix with cold, O 2 -rich seawater. Metals and sulfur combine to form metal-sulfide minerals: Mn. O 2, Fe. O(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 H 2 S + O 2 SO 4 ++ H+ + ATP n n Chemosynthetic (sulfur oxidizing) Thermophilic Bacteria (up to 120 o. C) Hot, anoxic, sulfide rich water mixes with Cold oxygenated water Hydrothermal Vents as origin of Life?

Bacteria from 120 o. C http: //mollie. berkeley. edu/~volkman/

Vent biological communities n n BACTERIA (Bacteria and Archea) 400 morphological invertebrate species • New species every 2 weeks during 25 years! n Evolutionary Origin • • n 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 n n CH 4 + O 2 CO 2 + H 20 +ATP CH 4 CH 3 - + H+ +ATP H 2 S + O 2 SO 4 ++ 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 n Symbiosis with Bacteria n n n Ingestion of Bacteria n n n Grazers (gastropod limpets and snails) Filter Feeders (vent shrimp, polychaete worms, amphipods, anemones) Predators n n tube worms Vent Mussels and vent clams Ventfish, octopus Scavengers n Crabs

Tube worms

http: //web. uvic. ca/%7 Everenat/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

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/Plume. Studies

Chemical Reactions • Depends on ambient temperature

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/m 2 � 1000 x greater than typical biomass observed on deep-sea floor � Geol 104/Bio. ES 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. � Geol 104/Bio. ES 154