deep sea Flashcards

1
Q

deep sea characteristics

A
  • Least understood ecosystem on the planet
  • > 200m
  • Av depth = 3800m, max depth = 11,000m
  • 64% of earth
  • Food supplys surface
  • 90% of ocean
  • Largest ecosystem on earth
  • 0.0001% explored
  • 28 habitats are currently known in deep sea e.g. cold water corals
  • Extremely high biodiversity – in 0.25m2 = 100sp
  • Est richness 500,000 – 100,000,000
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2
Q

what did Forbes propose in 1840

A

Azoic hypothesis - there’s no life below 600m

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3
Q

what kind of habitat is the majority of the deep sea

A

soft sediment

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4
Q

what supplies the deep sea with food

A

faecal pellets, floating algae, bodies of dumped fish -> most derived from surface layer

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5
Q

what is Seasonality of repro and abundance in the deep sea tied to

A

phytoplankton blooms at the surface

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6
Q

2 types of predominantly soft sediment environments

A

Continental margins
Abyssal plains

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7
Q

continental margin characteristics

A

(200 - 4,000m – 15% of seafloor) – shelf, slope, rise, abyss
- Impacted by trawling
- Studied minimal
- Heavily impacting areas of the seafloor before we have studied them
- OMZs

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8
Q

abyssal plains characteristics

A

(3800m - 75% of seafloor)
- <1% explored
- Magonese nodules
- Low energy
- Low accumulation rates
- 1-4 degrees c
- Generally high o2 concs

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9
Q

3 types of predominantly hard sediment environments

A

Seamounts
Canyons
Coral ecosystems

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10
Q

seamounts characteristics

A

Volcanic in origin
Isolated – currents
Geographic distance

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11
Q

Canyons characteristics

A
  • Oceanic island + continental margins
  • Conduits for transport of organic material into deep ocean
  • Significance:
    -structurally diverse habs - diversity hotspots
    -Larval sources to adjacent cont margins
    -Refuge from ocean acidification
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12
Q

4 types of Coral ecosystems

A
  • Shallow tropical coral reefs
  • Mesophotic reefs
  • Deep sea and cold water coral reefs (no zooxanthellae)
  • Deep sea and cold water coral beds / gardens
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13
Q

impotence of deep sea coral habitats

A
  • Largest structures or extensive beds created
    by living organisms
  • Great diversity of species
  • Habitats
  • Fisheries
  • Long-lived and slow growing, take 1000s of
    years to develop
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14
Q

reasons deep sea coral communities are in decline

A
  • Humans – greatest threat
  • Ocean Acidification – affect deep species first
  • Mining
  • Trawling - Rockhopper gear
    => even more in danger than shallow reefs
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15
Q

ecosystems that use chemosynthesis

A

hydrothermal vents
cold seeps
whale falls
sunken woods + org remains

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16
Q

hydrothermal vents characteristics

A
  • Spreading centres
  • High biomass (rich food source) but low diversity community (toxic – need to be specifically evolved)
  • Ephemeral 10s to 100 yrs
  • Fastest growing orgs
17
Q

cold seeps characteristics

A
  • Subduction zones
  • Cont margins – oil and gas reserves
  • Stable envs – last for 1000s of yrs
  • Slowest growing orgs
18
Q

whale falls characteristics

A
  • Bones have large lipid amounts
  • Last 100 yrs
  • Dispersal + evolutionary stepping stones for net/seep fauna
  • High diversity
  • Impacts of Whaling
19
Q

sunken wood characteristics

A
  • Most ephemeral
  • Least well-developed
  • Chemo community