Low oxygen environments

Question 1

Deep Sea Hydrothermal Vents 1

Answer 1

Microbial populations
High pressures
Outflow water temp 350 degrees
Ambient water temp 2 degrees
No sunlight - no photosynthesising
Some oxygen from mixing with sea water
Hydrogen sulphide and metals released
carbon fixing through chemosynthesis using hydrogen sulphide
some animals feed on chemosynthesising bacteria - many form symbiotic relationships

Question 2

Deep Sea Hydrothermal Vents 2

Answer 2

Oxygen consumed by reaction with sulphide
Life only possible where hot water mixes with sea water
Prokaryotes can occur up to 120 degrees
Metazoans exist below 50 degrees
Dominated by annelids, pogonophoran tubeworms, bivalve molluscs and crustaceans

Question 3

Deep Sea Hydrothermal Vents 3

Answer 3

Vents widely separated and short lived
Efficient dispersal of organisms
Can be colonised within 1 year of formation
Oocytes and larvae - large food reserves
Sulphide may act as attractant

Question 4

Adaptations of Vent Macrofauna

Answer 4

Spatially spanning the oxic/anoxic transition zone
Acquiring oxygen by pumping oxic water into anoxic burrow or tube
Large gills for gas exchange
Decreased diffusion distances between gas exchange surfaces and blood circulation
Efficient circulation
Respiratory pigments have very high oxygen affinities.