ZOOPLANKTON

Question 1

What are zooplankton?

Answer 1

• animals that are severely limited in their ability to overcome ocean currents and drift

Question 2

Distinguish between holoplankton and meroplankton

Answer 2

HOLO - do this for all of their life

MERO - subset of life history stages

Question 3

SIZE

Answer 3

• v v small

- 0.5mm to 15mm

Question 4

ACTIVITY LEVELS

Answer 4

• some simply drift in currents

- can control depths, many make vertical migrations

Question 5

Why vertically migrate?

Answer 5

1) Predator avoidance hypothesis

2) energy conservation hypothesis
- colder waters

3) current exploitation hypothesis
- allow water to refreshed

Question 6

Issues with predator avoidance hypothesis

Answer 6

still enough light for vision; bioluminescence, too deep

Question 7

Issues with energy conservation hypothesis

Answer 7

not held up by lab experiments

Question 8

Why is current exploitation hypothesis fairly accurate?

Answer 8

supported by patchiness of phytoplankton and zooplankton

Question 9

DISTRIBUTION

Answer 9

• mostly concentrated in photic zone because there will be lots of photosynthesising prey

Question 10

How do zooplankton remain buoyant?

Answer 10

1) add lighter-than-water material (gas, oil, fat)

2) replace heavier ions with lighter ones
eg. SO4- with Cl-

3) Increase surface area to volume ratio
(overall size, be flat, make projections)

Question 11

2 different forms for zooplankton to avoid predation

Answer 11

1. PASSIVELY
   - using spines
   - transparency
   - spines
   - appendages to increase apparent size
2. ACTIVELY
   - using nematocysts

Question 12

What are copepods? What are their lifecycles?

Answer 12

form of crustacean, the most abundant zooplankton

• graze bloom forming phytoplankton
• only adults at ocean surface
• development occurs at depth

Question 13

Give an example of a meroplankton

Answer 13

A jellyfish (Class Scyphozoa/ Phylum Cnidaria)

Question 14

Define larvae

Answer 14

Independent entities that develop from fertilised eggs and must undergo a drastic morphological change in order to become the adult form

Question 15

1) Example of herbivorous larvae

2) Example of carnivorous larvae

Answer 15

1) The veliger larvae of a marine snail

2) The zoea larvae of a shore crab

Question 16

Why have planktonic larvae?

Answer 16

• advantageous feeding + growth as planktonic environments are nutrient rich
• dispersal to new settling areas
• reduces competition intraspecifically
• increases species gene flow

Question 17

3 sources of primary production

Answer 17

1) phytoplankton (single celled algae)
2) macroalgae on shore
3) chemosynthetic bacteria

Question 18

What to phytoplankton provide energy for?

Answer 18

• pelagic communities
• shallow water benthic communities
• deep sea communities

Question 19

give an equation for primary production

Answer 19

primary production = light and warmth + inorganic nutrients

Question 20

Define Thermocline, a high one means what in terms of nutrient content…

Answer 20

Steep density gradient

• low nutrients, eg. when temp and light levels are high
• hence why algae bloom in spring

Question 21

Zooplankton predictions

1. Zooplankton no. will increase to take advantage of _____
2. Decreases in phytoplankton will lead to a decrease in _____
3. More species will produce planktonic larvae where…

Answer 21

1. increase in primary productivity
2. zooplankton
3. phytoplankton production is predictable

Question 22

What are the largest zooplankton?

Answer 22

scyphozoa, jellyfish