Plankton Sampling Flashcards
What is plankton
Living organisms that drift in the pelagic some of oceans and freshwater bodies
Extremely diverse group wide range of sizes and taxonomic groups
What are the two broad functional groups of plankton
Phytoplankton
Zooplankton
What’s phytoplankton
Predominately autotrophic, prokaryotic or eukaryotic algae.
Base of aquatic food chains
What’s zooplankton
Heyerotrophic unicellular and multicellular organisms.
Transfer energy from phytoplankton to higher trophic levels.
Name the 7 planktons
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
How is plankton collected in bottles
In shallow waters
Easy operate
Rate forms not usually collected
Doesn’t concentrate plankton
How is plankton collected in pumps
Why use a flow meter
It allows more accurate quantification of volume of water sampled
V = A*R / K
What is K in the equation for the volume of water filtered
Calibration constant
What is A in the equation for the volume of water filtered
Mouth area of the net
What is R in the equation for the volume of water filtered
Flow meter reading
When the net transverses through water column the equation for volume of water filtered is
V = A*d
d is the length of the water column transversed by the net
What’s the equation for estimating stock size using egg production methods
P = BRF
so
B = P/RF
What does each letter represent in the equation B = P/RF
P = total egg production of the stock
B = spawning stock biomass
R = proportion of the stock that are egg producing females
F = fecundity
What does fecundity mean
No. of eggs produced per unit weight of female
What is icthyoplankton
The eggs and larvae of fish
What gear considerations need to be made for sampling icthyoplankton
Usually sampled with plankton nets
Mesh size and method of deployment selected based on the size and development stage of target organisms
How is plankton collected with pumps
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
Advantages of plankton nets
Quick way to obtain concentrated sample
Range of designs from simple to complex
Potential problems with plankton nets
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
Name one Survey gear used for ichthyoplankton sampling
MOCNESS Designs
Multiple opening and closing net and environmental sensing system.
Allows sampling at multiple selected depths.
Why study icthyoplankton (early life stages)
Estimate abundance
Predict recruitment
Define stock boundaries
Understand recruitment process
Investigate ecology
