Deep Sea Adaptations (Guest Lecture)

Question 1

The sinking of the titanic helped to develop ___. How? What is it?

Answer 1

SONAR= sound navigation and ranging
b/c they wanted a technology to find the titanic

• sound bounces off of objects; can see shapes/ topography

Question 2

How was a lead line used to map the ocean floor?

Answer 2

a line was dropped off the ship with lead at the end (it dropped to the bottom)- then measured how far it went down
- one of the earliest methods for determining depth

Question 3

How does echo sounding map the ocean floor?

Answer 3

uses pulses of sound that rebound from the ocean floor

Question 4

How does side-scan sonar map the ocean floor? Give 2 advantages of this method

Answer 4

used fan-shaped pulses of sound to generate 3D maps over small areas
benefits:
-can map in swaths, not just certain points= easier to get an idea of a whole area
- high frequency gives high resolution

Question 5

echo sounding bounces back quickly from a ___ sea floor surface, and penetrates deeper into a ___ seafloor

Answer 5

rocky (little penetration)

muddy

Question 6

For accurate mapping, ____ scanning and ____ altimetry are used
For example, multibeam echo sounders use multiple ___ of sound ____

Answer 6

multibeam
satellite

frequencies
simultaneously

Question 7

How does satellite altimetry work? Why does this work?

Answer 7

measures the time taken by a radar pulse to travel from the satellite antenna to the surface of the ocean and back to the satellite receiver
- it doesn’t have to see through the water; it measures the height of the water itself

This works because water forms a ‘bump’ over underwater mountains because gravity causes attraction of water to the feature
- very accurate! up to 3cm

Question 8

When collecting specimens, the HMS challenger missed a lot of ___-___ animals. why?

Answer 8

soft bodied (gelatinous animals)
b/c they are fragile and they used aggressive collection

Question 9

pelagic=

Answer 9

lives in the water column of the sea

Question 10

Pelagic communities are further classified horizontally:
___= near shore
___= open water

Answer 10

neritic

oceanic

Question 11

The ocean can be classified by levels of light.
Areas where light penetrates= ____ zones
Areas with no light penetration= ___ zones

• the upper ___ zone is _photic, and the lower zone is __photic

Answer 11

photic

aphotic

upper photic zone= euphotic (lots of sunlight)
lower photic zone= dysphotic (much less sunlight- photosynthesis not possible but can use light to see a bit)

Question 12

The ___ wavelength is lost first as you go deeper into the ocean
___(long/short) wavelengths are lost first, and ___ remain at deeper depths

Answer 12

red
long
blue

Question 13

List the names of pelagic layers (shallowest to deepest) as you go down the water column

Answer 13

1. Epipelagic (continental shelfs ~200m
2. Mesopelagic (to 1000m)
3. Bathypelagic (1000-3000m)
4. Abyssopelagic (below 3000m)
5. Hadalpelagic (in a trench)

Question 14

The supply of nutrient-rich particles to the deep sea is ___(low/high). This depends on:
1
2
3

Answer 14

low

• distance from shore
• depth and time of travel of material from surface to bottom (decomp- deeper= more time to decompose)
• low primary production over remote deep sea bottoms

Question 15

organic matter flux in the deep sea comes from the ___

Answer 15

surface

ie input of organic matter from the water column declines with depth and distance from shore

Question 16

T/F
biodiversity changes linearly with depth

Answer 16

false!
the graph is an upside-down parabola

conditions at different depths determine what can live there

Question 17

Why are carnivorous animals less common in the abyssal bottoms?

Answer 17

fewer potential prey species
- they also need lots of oxygen to chase prey etc, and there is not much oxygen there

Question 18

t/f
the ocean is the most common living habitat in our biosphere

Answer 18

true!

Question 19

Physical characteristics of the pelagic deep sea:
1. No ___ deeper than 1000m
2. Mean temp= __C
3. constant ____ (34-35ppt)
4. ___ available except for ___ ___ zone

Answer 19

light (very dark)

3.5 (cold)

salinity

oxygen
oxygen minimum zone

Question 20

Physical characteristic of the pelagic deep sea:
1. gradients of inorganic nutrients are steep in the ____ zone
2. particles are lost as they ___ through the ___ zone
3. high ___ (increases by 1atm per __m depth)
4. some ____

Answer 20

mesopelagic
*important for upwelling

sink
mesopelagic

pressure
1atm/ 10m

seasonality

Question 21

nutrients may be high in areas where phytoplankton can’t grow. Why?

Answer 21

they’re not being taken out of the water by phytoplankton!

ie nutrients is not the limiting factor for phytoplankton growth (may be light etc)

Question 22

Azoic zone hypothesis=

Answer 22

conditions are so unfavorable in the deep sea that there should be no life down there

proved wrong by challenger etc

Question 23

Explain the accidental Alvin Lunchbox Experiment and what it implies

Answer 23

Lunch slipped offboard and sunk to 1500m- they recovered it months later and found it very well preserved

• greater preservation in the deep sea! From pressure? much slower decomp rate

Question 24

What is marine snow?

Answer 24

Non-living organic particles that are visible to us; detritus that has formed at the surface

(it’s the food!!)

Question 25

What is marine snow? List 5 things it can be

Answer 25

1. dead organisms (phytoplankton, kelp, pollen, insects, etc)
2. fecal pellets
3. mucus products (filter structure secreted by zooplankton like larvacean houses)
4. secretions of organisms
5. bubbles

Question 26

Give 2 reasons why marine snow is so important

Answer 26

1. microhabitat: for associated organisms; generally microorganisms are found at [high] where there’s marine snow (it’s a FOOD SOURCE)
2. transport: of surface derived organic matter to depth

Question 27

Why are crustacean fecal pellets so important?

Answer 27

they’re covered with a layer of polysaccharides; it’s a dense package that can sink to the bottom quickly

• They’re important for bringing nutrients and carbon to the seafloor quickly

Question 28

Explain the small scale ecological succession that occurs after marine snow enters the water

Answer 28

1. marine snow enters water
2. colonized by bacteria
3. bacteria decrease, colonized by flagellates
4. flagellates decrease, colonized by ciliates

Question 29

what are 3 advantages for organisms who interact with marine snow?

Answer 29

-food
- can use the buoyancy of marine snow to save energy
- travel on them= guaranteed dispersal for larvae etc

Question 30

Most carbon is remineralized in the upper 1000m of the sea- so how do mesopelagic/ deep sea organisms get food? List 5 ways

Answer 30

• detritus/ marine snow
• vertical migration to the surface to feed
• “ladder of vertical migration’ predation (daily migration of predators- they chase the herbivores who move up to feed)
• predation
• chemosynthesis at hydrothermal vents/ spreading zones

Question 31

What differences might you expect in 2 mesopelagic fish that live at the same depth, but one migrates up to feed and one doesn’t?

Answer 31

In the one that migrates:
- bigger eyes to see (more light up there)
- swim bladder to help with buoyancy
- well developed bones and muscles to swim up and big distances

opposite in the one that doesn’t migrate

Question 32

The 3 major adaptations to the deep sea have to do with (list 3)

Answer 32

feeding
mating
bioluminescence