Lecture 10: Deep sea vents

Question 1

Deep sea shrimp (Rimicaris exoculata) and bacteria

Answer 1

= ectosymbiotic associations with bacteria

• farming on the back
• shed ectoskeleton and then eat skeleton

Question 2

how do vents ‘die’

Answer 2

if local hydrothermal activity ceases or an eruption occurs

Question 3

Tubeworms when vents ‘die’

Answer 3

tubeworm larvae must be able to colonise new vents which may be 10-100km away

Question 4

lab study tubeworm colonisation

Answer 4

• larvae cultured at 2DC and 250 atmosphere (cold than vent, still = pressure)
• estimated survival of 38 days
• modelling studies show that larvae could colonise sites up to 100km away NOT FURTHER
• fast spreading vents (dont eat on the way)

Question 5

ocean currents aid in tubeworm colonisation post vent death

Answer 5

• ocean currents constrain embryo dispersal along the ridge
• larvae are therefore transported along the ridge improving their chances of survival)
• drawn towards other active geothermal sites

Question 6

larvae ___ contain symbionts

Answer 6

dont contain

Question 7

how are symbionts re-acquired to tubeworm larvae

Answer 7

• dont enter through mouth and gut, actually enter via the skin

Question 8

slow spreading vents, geothermal sites are __ apart

Answer 8

further

Question 9

deep sea shrimps: found where and movement between geothermal sites

Answer 9

• slow spreading sites (100km + apart)
• dispersale via larvae
• Larvae have eyes and feed on photosynthetic derived material

Question 10

cold seeps found in what conditions and whats found there

Answer 10

low temps and high pressures

• methane is found as methane hydrates
• CC a concern as heating = release methane

Question 11

Hesiocaeca methanicola (type of worm) and cold seeps

Answer 11

burrow through methane hydrates, presumably feeding on bacteria as they are not thought to contain symbionts

Question 12

Lamellibrachia luymesi (tube worm) from a cold seep

Answer 12

• 550m depth at gulf of mexico
• form association with microbes to use methane
• dye tubes with blue chitin stain to determine growth
• grow v v slowly, live 170-250 years
• longest lived animal on earth

Question 13

difference to tube worms at cold seeps and hot water vents

Answer 13

• sulphide doesnt enter the water column, instead it is taken up through the ‘root’ of the worm
• despite low temps, v high flux of sulphide through the system

Question 14

cold seep surface =

Answer 14

abundant bacterial mats on the seep surface

Question 15

sulphur flow in cold seeps

Answer 15

• methane can provide energy for sulphate reduction, but
  vestimentiferan tubeworms do not form symbioses with methane oxidising symbionts
• Aggregates of bacteria are found within the cold
  seeps.
  –Anaerobic sulphate reducing Bacteria
  –Anaerobic methane oxidising Archaea
  —> Archaea produce elemental S which is then used by bacteria
• sulphate must be recycled through the tubeworm root in order to provide sufficient sulphur for 200-250 years growth

Question 16

nitrogen fixation in cold seeps

Answer 16

• bac & Archaea also fix nitrogen

Question 17

the challenges of small and organisms stuck together =

Answer 17

• microbes as a ‘species’ incorrect they swap genes
• microbes form intimate associations with other microbes
  to allow complex metabolic interactions to occur
• Spatial heterogeneity (diverse in character) is high
• only scratched the surface on whats known