Deep Sea Communities

Question 1

when and where were hydrothermal vents found?

Answer 1

1977
Galapagos ridge using submersible Alvin

Question 2

what depth do hydrothermal vents occur?

Answer 2

below 1400m

Question 3

where do ocean ridges occur?

Answer 3

between the separation of two tectonic plates
- mid-ocean ridges and subduction zones

Question 4

what do hydrothermal vents require?

Answer 4

volcanic activity - magma for extreme heat

Question 5

what kind of habitats are vents?

Answer 5

reducing
- water seeps through ground and becomes heated and rises back up in chimneys at 350-400C

Question 6

what kind of metals are carried at high temps?

Answer 6

water carries more heavy metal including iron and sulfides

Question 7

why are they reducing habitats?

Answer 7

sulfate is reduced to sulfide

Question 8

what are plumes inhabited by?

Answer 8

bacteria and archaea

Question 9

what animals are abundant in vents?

Answer 9

tube worms
- Riftia pacifica
- annelids that use bacteria which helps create ecosystems around them
- secrete hard tubes and live in them

Question 10

describe tube worm

Answer 10

• beard of ciliated tentacles
• no segmentation in trunk region
• no functional gut as adults -> trophosome which has bacteria
• bacteria use energy obtained from oxidizing H2S and O2 to generate ATP
• worm eats bacteria (farms them in trophosome, digests them there)

Question 11

purpose of the tentacles

Answer 11

take up H2S and CO2 and O2 from water
- passes to the trophosome where it cultures the bacteria

Question 12

what’s the evidence they are annelid worms?

Answer 12

• larvae is a trochophore with a mouth and gut
• segmented opisthosoma (posterior portion of the body)

Question 13

describe larvae

Answer 13

mouth and gut and filter feed
near a vent they take up bacteria
gut is lost and develop trophosome
adult has no mouth and no gut but digest bacteria it farms in trophosome

Question 14

describe blind shrimp

Answer 14

Rimicaris exoculata
in hydrothermal vent in Atlantic Ocean
feed on symbiotic bacteria
obtain food
- 2 different areas -> one with bacteria for clear association with Fe-oxides, bacteria and some Fe-oxides
- gills
- no eyes
- visual organ -> sense black-body radiation from vent

Question 15

what is the visual organ?

Answer 15

structure that suggests there are photoreceptors but no-image forming has been found

Question 16

how does yeti crab get food?

Answer 16

farms chemosynthetic bacteria for food on its arms

Question 17

what are cold seeps?

Answer 17

• trenches in subduction
• based off continental slops
• similar to hydrothermal vents
• reduces chemicals present -> methane, hydrogen sulfide, ammonia
• supports large biomass based on chemosynthetic production
• low temps

Question 18

what is the main energy source in methane seeps?

Answer 18

methane

Question 19

what are whale falls?

Answer 19

dead whales sink to the ocean floor
skeleton decomposes anaerobically
methane bacteria grow on skeleton
vent animals settle on skeleton and feed off bacteria
-> nutrients fall down and use the nutrient filled sediment then bacteria come to colonize

Question 20

what is the bone eating worm name?

Answer 20

zombie worms - Osedax roseus
F larger than M
M found on bottom so little mates on the bottom

Question 21

deep water reefs

Answer 21

• sponge reefs
• continental shelf: deep cold reefs of glass sponges
• 1987
• previously thought to be extinct
• made of glass sponge reefs
• filter silica from water and forms a skeleton

Question 22

sponge reefs

Answer 22

• glass sponges built massive reefs during Jurassic forming 7000km belt along northern margin of Tethys Sea
• disappeared during cretaceous
• competition for silica by diatoms blamed for demise
• diatoms are planktonic and able to stay on surface and benefit from silica and photosynthesis

Question 23

sidescan sonar

Answer 23

sonar reefs are reflective and appear white

Question 24

what are sponge reefs?

Answer 24

• formed on boulders at edge of iceberg scours
• 35 Km long and 5-21 m thick
• living sponges up to 200 yrs old
• reefs as structures are up to 6000 yrs old determined by cores

Question 25

why only in Tethys Sea and in Canada?

Answer 25

substrate -> bare rock and light sediment to cement reef
silicate levels -> silica for skeleton
temp -> cold
light -> no light
food -> bacteria and flow - abundant on shelf

Question 26

deep water coral reefs

Answer 26

Lophelia pertusa
- most common
- colonial
- norwegian water
- found world wide
- deep and old
- dark
- cold water
- no algal symbionts

Question 27

threats to sponge reefs and cold water corals

Answer 27

• trawl fishing
• oil and gas exploration
• 50% of Norway’s cold-water corals are damaged by trawling