phytoplankton

Question 1

what are plankton

Answer 1

Any organisms that live in the water column and are incapable of swimming against a current

Question 2

what are nekton

Answer 2

able to swim independently of the current

Question 3

what are Phytoplankton

Answer 3

‘Plants’ – photosynthesisers – producers (major autotrophs at the base of marine foodwebs) - refered to as algae

Question 4

what are zooplankton

Answer 4

‘Animals’ – consumers – food web

Question 5

what are mixotrophs

Answer 5

Do a bit of both production and consumption

Question 6

3 major importances of plankton

Answer 6

Food production
climate change
eutrophication

Question 7

why is plankton important in food production

Answer 7

• Base of marine food web
• Major role in production of fish stocks, including shellfish – main source of protein

Question 8

why is plankton important in climate change

Answer 8

• Remove CO2 from surface waters
• Transfer to deep ocean
• Ocean = important sink for atmospheric CO2-

Question 9

what is the claw hypothesis

Answer 9

1.Phytoplankton create DMS when stressed (ocean warming)
2.DMS dissolves into water and enters atmos to create cloud condensation nuclei
3.Amount of sun that gets into water is reduced – negative feedback loop

Question 10

why is plankton important in eutrophication

Answer 10

Toxic
Harmful algal blooms
Fish, marine mammal & human mortalities

Question 11

how did phytoplanktons evolution start

Answer 11

All started in same way with chloroplasts – then organisms developed a different way they are able to photosynthesise

Question 12

an important group of autotrophic plankton in the ocean

Answer 12

cyanobacteria (formerly called blue-green algae)

Question 13

what are the two possible morphologies of phytoplankton

Answer 13

unicellular or colonial

Question 14

how can phytoplankton increase their niches

Answer 14

contain accessory pigments as well as chlorophyll that give them different colors (different in different plankton – determine where they can most effectively live)

Question 15

6 main phytoplankton groups

Answer 15

Diatoms
Dinoflagellates
Noctiluca
Coccolithophores
Nanoflagellates
Prokaryotes

Question 16

diatom characteristics

Answer 16

• Bacillariophyceae
• Non-motile
• cellulose cell wall + Silica cell wall (frustule - top bit slides over bottom bit)
• If no mixing -> sink
• Grow well in mixed conditions - High growth rates
• Dominate spring blooms
• Centric diatoms- radial symmetry
• Pennate diatoms- lateral symmetry
• Siliceous frustule - contribute silica to deep-sea sediments
• Many have beautiful ornamentation that can be used in species identification

Question 17

What kind of symmetry do centric and pennate diatoms have

Answer 17

• Centric diatoms- radial symmetry
• Pennate diatoms- lateral symmetry

Question 18

diatom reproduction characteristics

Answer 18

Asexual – mitosis
- Large and small bits are generated in the mitosis splitting – if left with the small parts, diatom size will shrink – results in big range of size in species
- When diatoms get too small to undergo biological processes, they use sexual reproduction

Question 19

dinoflagellate characteristics

Answer 19

• Successful in stratified water
• Migrate: light – nutrients
• Some species toxic
• ~50% heterotrophic
• Possess flagella (hence motility)
• Can tolerate low light level
• Some are mixotrophic; i.e., they can be autotrophic and heterotrophic at the same time
• Some have cellulosic thecate plates in specific number and arrangement that can be used in species identification

Question 20

Noctiluca characteristics

Answer 20

• Autotrophs - but do feed aswell
• Responsible for biolumenecense

Question 21

explain how some dinoflagellates and diatoms are responsible for causing Ciguatera Fish Poisoning: CFP

Answer 21

• When fish pick up macroalgae to feed on, they eat these dinoflagellates aswell
• Dinoflagellate toxins will build up in their flesh and be passed to other fish that eat those fish aka fish sold to us
• Can also cause numerous Shellfish Poisonings (PSP, NSP, DSP, ASP) - europe require standard testing for these

Question 22

Coccolithophores characteristics

Answer 22

• Unicellular phytoplankton covered in coccoliths (made of calcium carbonate)
• Subset of dinoflagellates (still have flagella)
• Prymnesiophyceae
• CaCO3 scales = coccoliths
• A globally significant species = Emiliania huxleyi
  Important role in marine carbon + sulphur cycles

Question 23

Nanoflagellates characteristics

Answer 23

• 2-20 mm
• HNAN (heterotrophic) & PNAN (photosynthetic)
• Prymnesiophytes, chrysophytes, cryptophytes, chlorophytes etc
• Successful in oligotrophic waters - smaller size (+ high surface area:volume ratio) - able to take in the small amounts of nutrients
• Grazed on by protozoan predators

Question 24

what phytoplankton are prokaryotic

Answer 24

Cyanobacteria
viruses

Question 25

prokaryote cyanobacteria characteristics

Answer 25

• Formerly called blue-green algae
• Dominate oligotrophic waters
• Prochlorococcus:
  smallest phototroph
  30-80% PP oligotrophic
• Trichodesmium: fix N
• Synechococcus

Question 26

prokaryote viruses characteristics

Answer 26

• Live off other organisms
• Latch onto cell, inject copies of themselves into cell + take over to make more copies of themselves until they rupture and release them
• Proper recognition: 1990’s
• Small, C & N rich particles
• Infect & lyse specific host organisms
• Cell lyses: divert particulate production of hosts into DOM
• Bacteriophages: impact on bacterial community

Question 27

what was found in Mesocosm experiments - Bratbak et al. (1992)

Answer 27

• 72% of bacterial production removed by viral lysis
• Loss rate exceeded grazing by flagellates
• Cell lysis resulted in release of proteins, nucleic acids & organic compounds
• After extracellular breakdown: DOM (nutrients) released and available to sustain bact & phyto
  Important:
  1) May be of quantitative sig: nutrient flow
  2) Exert a species specific control: structure food web