Aquatic Communities

Question 1

Holoplankton

Answer 1

Spend entire life cycle as plankton.

Question 2

Meroplankton

Answer 2

Spend only part of life cycle as plankton (usually larvae of adults in Benthic Realm).

Question 3

Phytoplankton

Answer 3

Free-floating organisms capable of photosynthesis.

Question 4

Zooplankton

Answer 4

Free-floating organisms with limited locomotion.

Question 5

Bacterioplankton

Answer 5

Free-floating bacteria and blue-green algae.

Question 6

Viroplankton

Answer 6

Free-floating viruses.

Question 7

Epibenthic

Answer 7

Organisms on or above the bottom of the ocean.

Question 8

Infauna

Answer 8

Organisms below sediment surface.

Question 9

What are the 3 classes of infauna?

Answer 9

1. Macrofauna: > 0.5 mm
2. Meiofauna: 0.062-0.5 mm
3. Microfauna: <0.062 mm

Question 10

Equal Chance (Lottery) Hypothesis

Answer 10

Larvae of different species have an equal chance of settling on an open spot.

• Limited space but species competitvely equal
• First to settle is able to retain spot

Question 11

What are the Pelagic Zone’s separate components and what criteria define them?

Answer 11

From top to bottom:

1. Epipelagic: lower limit is where photosynthesis equals carbon waste (respiration) [surface to 100-200 m]
2. Mesopelagic: lower limit where water equals 10ºC [700-1000 m]
3. Bathypelagic: lower limit where the water equals 4ºC [2k-4k m]
4. Abyssopelagic: All water under the bathypelagic level, excluding trenches.
5. Hadalpelagic: Trench water [>6k m]

Question 12

What are the Benthic Zone’s separate components and what criteria define them?

Answer 12

From top to bottom:

1. Shelf: emcompasses the land depth equivalent to the combined epipelagic and mesopelagic realms
2. Bathyal: land that covers the same depth limits as the bathypelagic realm.
3. Abyssal: land that covers the same depth limits as the abyssolpelagic realm.
4. Hadal: trench land [>6k m]

Question 13

Nekton

Answer 13

Animals capable of moving against water flow

Question 14

Plankton

Answer 14

Organisms incapable of moving aginst water flow.

Question 15

Epibenthic

Answer 15

Organisms on or above the bottom surface of a marine body.

Question 16

Infauna

Answer 16

Organisms below the sediment surface.

• Macrofauna: >0.5 mm
• Meiofauna: 0.062-0.5 mm
• Microfauna: <0.032 mm

Question 17

Net Primary Production (NPP)

Answer 17

The amount of plant matter produced per unit area of the earth’s surface per unit time.

Question 18

What is the ultimate fate of oceanic kelp?

Answer 18

• ~5% is consumed within the kelp forest itself.
• ~95% is exported out of the forest to adjacent ecosystems.
  
  • Greatest export occurs during large wave events.

Question 19

Giant kelp accounts for __% of the particulate carbon reaching the deep sea floor and __% of the diet of sea urchins that live there.

Answer 19

80; 60

Question 20

Amensalism

Answer 20

A (0, -) relationship.

• An example is the amensalic relationship between deposit feeders and suspension feeders, whereby the fine particles that deposit feeders stir up via bioturbation end up clogging the feeding apparatus of suspesion feeders.

Question 21

Stipate Kelp

Answer 21

Possess a thick, rigid stipe and small holdfast.

• Extend up to 2m off the bottom to produce a subsurface canopy.

Question 22

Giant kelp has a(n) _____ _____ effect on understory algae and a(n) _____ _____ effect on sessile invertebrates.

Answer 22

direct negative; indirect positive

The kelp shading limits understory algae growth, which in turn promotes sessile invertebrate expansion.

Question 23

What are the two classes of the tidal cycle?

Answer 23

1. Daily: Typically semi-diurnal (2 high and low tides)
2. Lunar: alternates between spring and neap tide series

• 2 Spring and 2 Neap every ~29 days as the moon rotates around the Earth
• Spring Tide: greater tidal amplitude
• Neap Tide: smaller tidal amplitude

Question 24

Recruitment Limitation

Answer 24

The supply of new individuals of any species is low, and thus no one species dominates.

• Abundant resources → weak competition
• No exclusion

Question 25

Storage Effect (Lottery)

Answer 25

Since the settlement of new recruits generally fluctuates greatly, periodic high recruitment can result in persistance.

Question 26

Meiofauna are found exclusively in ______ communities.

Answer 26

Soft bottom

Question 27

Average particle size _____ with increased water flow.

Answer 27

increases; high water flow also typically leads to more frequent disturbances.

Question 28

Give 3 examples of deposit feeder types.

Answer 28

1. Surface browsers: have tentacles or siphons and ingest surface sediment.
2. Head-down deposit feeders: ingest particles at depth and defecate at surface.
3. Mobile browsers: burrow in sediment ingesting and defecating.

Question 29

Shallow seas have a higher proportion of _____ feeders, while deep seas have a higher proportion of _____ feeders.

Answer 29

suspension; deposit

Question 30

Initial colonizers of soft bottom communities tend to be _____ _____ species, while later colonizers tend to be _____ _____ species.

Answer 30

surface dwelling; deep burrowing

Question 31

What are the two components of diversity?

Answer 31

1. Species Richness: number of different species present.
2. Species Evenness: distribution of relative abundances among the species.

Question 32

What are two important niche aspects?

Answer 32

1. Niche Breadth: how broad the range of conditions within which a species can survive, grow and reproduce
2. Niche Overlap: degree to which different species require the same resources.