The Deep Sea Benthos and Hydrothermal Vents
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Transcript The Deep Sea Benthos and Hydrothermal Vents
Deep-Sea
Hydrothermal Vent Communities
Comparison with Other
Deep-Sea Benthic Environments
Most deep-sea environments are characterized by:
�Low availability of food
No light, no photosynthesis
Falling remains of dead organisms, decaying organic matter
�Low (0-2°C), relatively constant temperature
�High pressure (400-500 times atmospheric)
Summary of General Biological Characteristics
of Deep-Sea Macrofauna
� Reproduction and Development
Late reproductive maturity
Slow development
� Physiology
Low metabolic rate and activity level
� Ecological
Long lived species
Low population densities, but high species diversity
Hydrothermal Vents
� Vents are associated with mid-ocean ridges, spreading
centers.
� Cold waters percolate into crust and are geothermally
heated before being vented at very high temperatures.
� Vent waters are not only hot, but low in oxygen and rich
in metals and hydrogen sulfide.
Black and White Smokers
Hydrothermal Vent Distribution
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
Hydrothermal Vent
Macrofauna: Worms
Vestimentiferan worms
(Riftia pachyptila )
Serpulid polychaete worms
Hydrothermal Vent
Macrofauna: Bivalves
Giant clams
(Calyptogena magnifica)
Mussels
(Bathymodiolus thermophilus)
What supports this abundance of life around
hydrothermal vents? What is the energy
source for this ecosystem?
Chemosynthesis
�Basis of life around deep sea hydrothermal
vents is chemosynthesis rather than
photosynthesis.
Chemical energy rather than solar energy
supports the ecosystem.
Bacteria rather than plants are the primary
producers.
Vent Ecosystems Depend on
2 Types of Bacteria:
Free-living bacteria
Geol 104/BioES 154
Symbiotic bacteria
Tube Worm:
Riftia pachyptila
� Unusual animal
No mouth
No anus
No digestive tract
Dependent upon bacteria
living in its gut
Gills extracts hydrogen
sulfide, carbon dioxide &
oxygen from seawater;
blood delivers these to
gut
In return, bacteria
provide nourishment for it
Hydrothermal Vent Macrofauna: Environmental
Constraints on Life Cycles and Reproduction
� Suitable vent environments for these
organisms are rare.
� Individual vents have short lifespans.
� Volcanic eruptions and earthquakes
pose further hazards.
�These conditions favor rapid growth
rates, continuous reproduction.
Geol 104/BioES 154
Geol 104/BioES 154
Geol 104/BioES 154
Geol 104/BioES 154
Geol 104/BioES 154