Lecture 11: Deep sea biogenic habitats Flashcards Preview

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Flashcards in Lecture 11: Deep sea biogenic habitats Deck (14)
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1
Q

__% of our world is ocean

A

71%

2
Q

average depth of ocean is ___M

A

3794m (nearly 4 kilometres )

3
Q

__% of the ocean is >1000m deep

A

85%

4
Q

deep sea ecosystems as nutritional _____

A

deserts

  • little food, no light so no photosynthesis
  • all food derived from the sinking of organic matter
  • majority is tiny, particulate organic carbon (POC)
5
Q

deep sea ecosystem food source

A
  • particulate organic carbon (POC)

- some massive inputs i.e. dead whales

6
Q

limiting factor to deep sea ecosystems

A

food

7
Q

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

A

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

8
Q

stages post dead whale fall

A
  • 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

9
Q

zombie worms

A
  • 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
10
Q

whale falls and other large animal carcasses constitute an important

A

input of food into the deep sea

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

11
Q

terrestrial food in the deep sea: wood

A
  • 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
12
Q

deep sea wood falls =

A
  • floats, becomes saturated and sinks
  • increasing pressure squeezes air out and sinks faster
  • rich input of food to deep sea desert
13
Q

wood as a food source

A
  • not easily digested by many organisms
  • but specialists communities have evolved to exploit it
  • bacteria & wood-boring molluscs (Xylophaga) are key players
14
Q

wood digestion stages =

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