Lecture 11: Deep sea biogenic habitats

Question 1

__% of our world is ocean

Answer 1

71%

Question 2

average depth of ocean is ___M

Answer 2

3794m (nearly 4 kilometres )

Question 3

__% of the ocean is >1000m deep

Answer 3

85%

Question 4

deep sea ecosystems as nutritional _____

Answer 4

deserts

• little food, no light so no photosynthesis
• all food derived from the sinking of organic matter
• majority is tiny, particulate organic carbon (POC)

Question 5

deep sea ecosystem food source

Answer 5

• particulate organic carbon (POC)

- some massive inputs i.e. dead whales

Question 6

limiting factor to deep sea ecosystems

Answer 6

food

Question 7

massive food inputs i.e. dead whales how much?

Answer 7

each fall is a bonanza for deep sea life, equivalent to 200 years of background food input
- each whale becomes its own ecosystems

Question 8

stages post dead whale fall

Answer 8

• scavengers –> strip carcass down i.e. hagfish, sharks
• opportunists –> i.e. shrimp, zombie worms
• sulfophilic stage —> bacteria symbiotic w mussels, tube worms, clams

– takes years

Question 9

zombie worms

Answer 9

• Osedax worms
• bone eating worms (digest the bone itself)
• feed on animal carcasses
• bacteria symbionts -
• specific feeding traces for each species, can look back in history at old whale falls to see which species present and which bones are favoured by which species

Question 10

whale falls and other large animal carcasses constitute an important

Answer 10

input of food into the deep sea

- support unique & general organisms form scavengers to osedax worms (zombie worms)

Question 11

terrestrial food in the deep sea: wood

Answer 11

• taken downstream from rivers into the sea
• huge quantities
• storms = increase amount (i.e tropical storms)
• human activity increasing this i.e. shipwrecks, forest destruction, climate change

Question 12

deep sea wood falls =

Answer 12

• floats, becomes saturated and sinks
• increasing pressure squeezes air out and sinks faster
• rich input of food to deep sea desert

Question 13

wood as a food source

Answer 13

• not easily digested by many organisms
• but specialists communities have evolved to exploit it
• bacteria & wood-boring molluscs (Xylophaga) are key players

Question 14

wood digestion stages =

Answer 14

• specialist bacteria, wood boring bivalves & opportunistic fauna (1-2 months)
• boring-bivalves attraction for settlement of other organisms
• sulfophilic stage
• – create their own community