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Geol104/BioES154
Deep-Sea Deep-Sea Hydrothermal Vent Hydrothermal Vent
CommunitiesCommunities
Geol 104/BioES 154
Comparison with Other Comparison with Other Deep-Sea Benthic EnvironmentsDeep-Sea Benthic Environments
Most deep-sea environments are characterized by:Most deep-sea environments are characterized by:�Low availability of foodLow availability of food
No light, no photosynthesisNo light, no photosynthesisFalling remains of dead organisms, decaying organic matterFalling remains of dead organisms, decaying organic matter
�Low (0-2°C), relatively constant temperatureLow (0-2°C), relatively constant temperature�High pressure (400-500 times atmospheric)High pressure (400-500 times atmospheric)
Geol 104/BioES 154
Summary of General Biological Summary of General Biological Characteristics of Deep-Sea MacrofaunaCharacteristics of Deep-Sea Macrofauna
�Reproduction and DevelopmentLate reproductive maturitySlow development
�PhysiologyLow metabolic rate and activity level
�EcologicalLong lived speciesSlow colonization ratesLow population densities, but high species diversity
Geol 104/BioES 154
Hydrothermal VentsHydrothermal Vents� Vents are associated with mid-ocean ridges, spreading Vents are associated with mid-ocean ridges, spreading
centers.centers.� Cold waters percolate into crust and are geothermally Cold waters percolate into crust and are geothermally
heated before being vented at very high temperatures.heated before being vented at very high temperatures.� Vent waters are not only hot, but low in oxygen and rich Vent waters are not only hot, but low in oxygen and rich
in metals and hydrogen sulfide.in metals and hydrogen sulfide.
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Hydrothermal Vent CommunitesHydrothermal Vent Communites� 25 years of exploration have revealed:25 years of exploration have revealed:
A new phylumA new phylum At least 20 new familiesAt least 20 new families Over 90 new generaOver 90 new genera Over 300 new speciesOver 300 new species Over 250 new strains of Over 250 new strains of free-living bacteriafree-living bacteria
� BiomassBiomass Up to 30 kg/mUp to 30 kg/m22
1000 x greater than 1000 x greater than typical biomasstypical biomassobserved on observed on deep-sea floordeep-sea floor
Geol 104/BioES 154
Vestimentiferan worms Vestimentiferan worms ((Riftia pachyptilaRiftia pachyptila ) )
Serpulid polychaete wormsSerpulid polychaete worms
Hydrothermal Vent Hydrothermal Vent Macrofauna: WormsMacrofauna: Worms
Geol 104/BioES 154
Giant clams Giant clams ((Calyptogena magnifica)Calyptogena magnifica)
Mussels Mussels ((Bathymodiolus thermophilus)Bathymodiolus thermophilus)
Hydrothermal Vent Hydrothermal Vent Macrofauna: BivalvesMacrofauna: Bivalves
Geol 104/BioES 154
What supports this abundance of life What supports this abundance of life around hydrothermal vents? What is around hydrothermal vents? What is the energy source for this ecosystem?the energy source for this ecosystem?
Geol 104/BioES 154
ChemosynthesisChemosynthesis�Basis of life around deep sea hydrothermal Basis of life around deep sea hydrothermal
vents is vents is chemosynthesischemosynthesis rather than rather than photosynthesis.photosynthesis. Chemical energy rather than solar energy Chemical energy rather than solar energy
supports the ecosystem.supports the ecosystem. Bacteria rather than plants are the primary Bacteria rather than plants are the primary
producers.producers.
�Aerobic Aerobic chemoautolithotrophychemoautolithotrophy COCO22 + H + H22S + OS + O22 + H + H22O O CHCH22O] + HO] + H22SOSO44
Organisms must have adaptations to preventOrganisms must have adaptations to prevent
sulfide from poisoning oxygen binding site.sulfide from poisoning oxygen binding site.
Geol 104/BioES 154
Vent Ecosystems Depend on Vent Ecosystems Depend on 2 Types of Bacteria:2 Types of Bacteria:
Free-living bacteriaFree-living bacteria Symbiotic bacteriaSymbiotic bacteria
Geol 104/BioES 154
Tube Worm: Tube Worm: Riftia pachyptilaRiftia pachyptila
� Unusual animalUnusual animal No mouthNo mouth No anusNo anus No digestive tractNo digestive tract Dependent upon bacteria Dependent upon bacteria
living in its gut or living in its gut or ““troposometroposome””
Gills extracts hydrogen Gills extracts hydrogen sulfide, carbon dioxide & sulfide, carbon dioxide & oxygen from seawater; oxygen from seawater; blood delivers these to blood delivers these to troposometroposome
In return, bacteria provide In return, bacteria provide nourishment for nourishment for RiftiaRiftia
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Giant Clam: Giant Clam: Calyptogena magnificaCalyptogena magnifica
Symbiotic bacteria in gills.Symbiotic bacteria in gills. High hemoglobin content High hemoglobin content
in blood.in blood.
Clams on the half shell anyone?Clams on the half shell anyone?
Geol 104/BioES 154
Hydrothermal Vent Macrofauna: Hydrothermal Vent Macrofauna: Environmental Constraints on Life Cycles Environmental Constraints on Life Cycles
and Reproductionand Reproduction
� Suitable vent environments for these Suitable vent environments for these organisms are rare.organisms are rare.
� Individual vents have short life-Individual vents have short life-spans.spans.
� Volcanic eruptions and earthquakes Volcanic eruptions and earthquakes pose further hazards.pose further hazards.
�These conditions favor rapid growth These conditions favor rapid growth rates, continuous reproduction, and rates, continuous reproduction, and high fecundity.high fecundity.