The Marine Plankton

Question 1

pelagic zone

Answer 1

The entire water column, ranging from the surface photic zone to the abyssal depths

Question 2

benthic zone

Answer 2

the substrate mud, rock, sand (the floor of the sea and ocean)

Question 3

pelagic organisms

Answer 3

nekton (pelagic, can maintain their position in water currents), plankton (pelagic, cant maintain position in water currents), phytoplankton (plant like), zooplankton (animal like)

Question 4

mega-plankton

Answer 4

20cm+

Question 5

Macro-plankton

Answer 5

2-20cm

Question 6

Meso-plankton

Answer 6

200µm-2cm

Question 7

Micro-plankton

Answer 7

20-200µm

Question 8

Nano-plankton

Answer 8

2-20µm

Question 9

Pico-plankton

Answer 9

0.2-2µm

Question 10

Phytoplanktonic organisms

Answer 10

Diatoms, Dinoflagellates, Coccolithophorids, Cyanobacteria

Question 11

Diatoms

Answer 11

Single celled eukaryotes, capable of photosynthesis. Can also occur as single cells or chains. 5-200um and fast growing (1-3 generations per day)
Characterized by producing a silica box around the cell, have spikes to prevent predation, aid buoyancy
The major primary producers in coastal waters
Important food source for zooplankton and larval fish.

Question 12

Dinoflagellates

Answer 12

Single celled, characterised by two whip like flagella. Some r armoured with cellulose plates, others r naked. They fulfill many ecological roles, some are phytoplankton, some are zooplankton, some are both (mixotrophy).
Can eat smaller cells and are food for larger zooplankton.
Can form harmful blooms
Bloom forming species can cause disease in wildlife and humans (eg., Pfiesteria hysteria).

Question 13

Mixotrophy

Answer 13

Mixotrophy allows a species to be both plant and animal like

Question 14

Coccolithophorids

Answer 14

Single celled eukaryotes (protists) capable of photosynthesis.
Typically small and characterized by calcium carbonate coccoliths.
Ecologically important primary producers in coastal and open ocean waters. Form blooms that look chalky white in open ocean. Major contribution to calcium carbonate sedimentation.

Question 15

Cyanobacteria

Answer 15

Capable of photosynthesis, are typically <1 to ~5 micrometers in size.
Many can use N2 gas as a source of nitrogen (they fix nitrogen).
Can occur as single cells, filaments or colonies.
The dominant primary producer in the oceans, many are food for small zooplankton.
Some are toxic, and if they bloom can impact whole ecosystems.

Question 16

Viruses and bacteria

Answer 16

Viruses most abundant life form in ocean. Major source of mortality and disease in organisms.
Bacteria are important heterotrophic decomposers. Bacteria play a critical role in major element cycles.

Question 17

Microzooplankton

Answer 17

Small metazoan and protazoa form a critical link in marine food webs. Consume bacteria and nano-phytoplankton. Feed mesozooplankton and larval fish

Question 18

Cilliates

Answer 18

Characterised by hair like cillia on the cell surface associated with movement and feeding.
Important grazers in marine plankton

Question 19

Larval metazoans

Answer 19

Many animals produce planktonic larvae which are highly abundant

Question 20

Mesozooplankton

Answer 20

Exclusively metazoan, most animal phyla are represented in plankton but 1 dominant group.
Copepods are small crustaceans and account for 95% of the planktonic biomas. Dominant taxonomic group in plankton. Highly diverse, 3 major groups: Harpacticoids, cyclopoids, calanoids. Most important grazers of the primary producers, important egesters too (CRAP). A major pathway for carbon export to the deep oceans.