Plankton

Question 1

Define planktonic

Answer 1

Wandering, that which is caused to wander.

Question 2

Define plankton

Answer 2

Living organisms which drift in the pelagic zones of oceans and bodies of freshwater.

Question 3

Why are plankton diverse?

Answer 3

There are a wide range of sizes and taxonomic groups.

Question 4

What are the two broad functional groups of plankton?

Answer 4

Phytoplankton
Zooplankton

Question 5

What are the features of phytoplankton?

Answer 5

-Predominantly autotrophic (photosynthetic)
-Prokaryotic or eukaryotic algae
-Base of aquatic food chains

Question 6

What are the features of zooplankton?

Answer 6

-heterotrophic unicellular/multicellular organisms
-transfer energy from phytoplankton to higher trophic levels

Question 7

What are holoplankton?

Answer 7

Organisms that spend their entire life cycles in the plankton

Question 8

What are mecroplankton?

Answer 8

Organisms that only spend part of their life cycles in the plankton

Question 9

What are examples of Megaplankton?

Answer 9

Jellyfish, Ctenophores
Plankton that are >20mm - 2m

Question 10

What are examples of Macroplankton?

Answer 10

Fish larvae, krill
2-20 mm

Question 11

What are examples of Mesoplankton?

Answer 11

Copepods, fish eggs
0.2-2mm

Question 12

What are examples of Microplankton?

Answer 12

Rotifera
20-200um

Question 13

What are examples of Nanoplankton?

Answer 13

Diatoms, dinoflagellates
2-20um

Question 14

What are examples of pictoplankton?

Answer 14

Cyanobacteria
0.2-2um

Question 15

What is an example of Femtoplankton?

Answer 15

Marine viruses
<0.2um

Question 16

What are the plankton collection methods?

Answer 16

-Bottles
-Pumps
-Nets

Question 17

Describe the bottle collection method?

Answer 17

In shallow waters, simple weighted bottles or tubes can be used to collect water (and plankton).
Van Dorn design allows sampling at specific depths.

Question 18

What are the benefits of bottle sampling?

Answer 18

-Easy to operate
-Sampling depths are accurately known
-Sediment or filtration can be used to concentrate plankton from fixed water samples

Question 19

What are the negatives about bottle sampling?

Answer 19

-Rare plankton are not usually collected
-Does not concentrate plankton

Question 20

What is the process of net sampling?

Answer 20

Water is pumped on to boat or pier through a filtration net.

Question 21

What is the benefit of net sampling? (V)

Answer 21

Volume of water filtered can be accurately quantified.

Question 22

What are the negatives about net sampling?

Answer 22

-Larger zooplankton can be damaged by pumping.
-Not suitable for sampling deeper waters.

Question 23

What are the benefits of net sampling?

Answer 23

• Quick way of obtaining the sample
• Range of designs from simple to complex

Question 24

What are the negatives about net sampling?

Answer 24

• Quantification is difficult
• Fishing depth can be hard to control
• Selectivity- net mesh too large

Question 25

What are the three directions a plankton net tow may be?

Answer 25

Horizontal, oblique and vertical

Question 26

What is the speed required for horizontal or oblique tows with standard nets?

Answer 26

1.5 to 2.0 knots. Filtration is less effective and risk of net damage at higher speeds.

Question 27

When is the best time for horizontal net sampling?

Answer 27

Before dawn, after dusk or at night. Zooplankton move to deeper layers during daylight hours.

Question 28

What are depressors used for in net sampling?

Answer 28

Stabilising the net in strong currents.

Question 29

Why is washing the net after every hauling important?

Answer 29

-Prevents clogging of the net. - Prevents contamination

Question 30

What are the closing mechanisms used on nets?

Answer 30

- messengers - electric - acoustic -time -pressure release mechanisms

Question 31

What is the benefit of having a closing mechanisms on a net?

Answer 31

It allows to sample at selected depth.

Question 32

What is a Nansen net?

Answer 32

Single closing net

Question 33

What is a MOCNESS?

Answer 33

Multiple Opening/Closing Net and Environmental Sensing System.

Question 34

What is a CUFES?

Answer 34

Continuous underway fish egg sampler

Question 35

What does a CUFES consist of?

Answer 35

A machine that pumps a sample of water from the top 3 meters of the water continuously while the ship is moving. A filtration system traps all of the floating fish eggs which are collected and identified on board.

Question 36

How are fish eggs identified after collection by CUFES?

Answer 36

They can be identified manually or by a camera and image recognition system which also counts the eggs.

Question 37

What are the types of fixatives for plankton?

Answer 37

-Formaldehyde -Lugol’s Iodine

Question 38

What are the methods for quantifying plankton in sample?

Answer 38

- volumetric method - gravimetric method - sedimentation chambers

Question 39

Name the methods used for species identification of plankton samples

Answer 39

- sub-sampling -using keys -importance of taxonomic skills - technological aids: automated ID

Question 40

What are the more specialised design plankton sampling methods?

Answer 40

-Nansen net - MOCNESS - Gulf VII sampler - Bongo net - Continous underway fish egg sampler