Plankton Sampling

Question 1

What is plankton

Answer 1

Living organisms that drift in the pelagic some of oceans and freshwater bodies
Extremely diverse group wide range of sizes and taxonomic groups

Question 2

What are the two broad functional groups of plankton

Answer 2

Phytoplankton
Zooplankton

Question 3

What’s phytoplankton

Answer 3

Predominately autotrophic, prokaryotic or eukaryotic algae.
Base of aquatic food chains

Question 4

What’s zooplankton

Answer 4

Heyerotrophic unicellular and multicellular organisms.
Transfer energy from phytoplankton to higher trophic levels.

Question 5

Name the 7 planktons

Answer 5

Megaplankton >20mm-2m jellyfish
Macroplankton 2-20mm fish larvae
Mesoplankton 0.2-2mm copepods
Microplankton 20-200um rotifer
Nanoplankton 2-20um diatoms
Picoplankton 0.2-2um Cyanobacteria
Femtoplankton <0.2 um marine viruses

Question 6

How is plankton collected in bottles

Answer 6

In shallow waters
Easy operate
Rate forms not usually collected
Doesn’t concentrate plankton

Question 7

How is plankton collected in pumps

Question 8

Why use a flow meter

Answer 8

It allows more accurate quantification of volume of water sampled
V = A*R / K

Question 9

What is K in the equation for the volume of water filtered

Answer 9

Calibration constant

Question 10

What is A in the equation for the volume of water filtered

Answer 10

Mouth area of the net

Question 11

What is R in the equation for the volume of water filtered

Answer 11

Flow meter reading

Question 12

When the net transverses through water column the equation for volume of water filtered is

Answer 12

V = A*d

d is the length of the water column transversed by the net

Question 13

What’s the equation for estimating stock size using egg production methods

Answer 13

P = BRF
so
B = P/RF

Question 14

What does each letter represent in the equation B = P/RF

Answer 14

P = total egg production of the stock
B = spawning stock biomass
R = proportion of the stock that are egg producing females
F = fecundity

Question 15

What does fecundity mean

Answer 15

No. of eggs produced per unit weight of female

Question 16

What is icthyoplankton

Answer 16

The eggs and larvae of fish

Question 17

What gear considerations need to be made for sampling icthyoplankton

Answer 17

Usually sampled with plankton nets
Mesh size and method of deployment selected based on the size and development stage of target organisms

Question 18

How is plankton collected with pumps

Answer 18

Water pumped into boat/pier through filtration net
Vol of water filtered can be accurately quantified
Larger zooplankton can get damaged by pumping
Not suitable for sampling deeper waters

Question 19

Advantages of plankton nets

Answer 19

Quick way to obtain concentrated sample
Range of designs from simple to complex

Question 20

Potential problems with plankton nets

Answer 20

Back pressure: reverse cone at mout reduced this
Quantification difficult - flow meter help to determine vol water filtered
Fishing depth - difficult to control
Selectivity: smallest mesh size 15um
….. net avoidance

Question 21

Name one Survey gear used for ichthyoplankton sampling

Answer 21

MOCNESS Designs
Multiple opening and closing net and environmental sensing system.
Allows sampling at multiple selected depths.

Question 22

Why study icthyoplankton (early life stages)

Answer 22

Estimate abundance
Predict recruitment
Define stock boundaries
Understand recruitment process
Investigate ecology