Lecture 1

Question 1

What is a CTD?

Answer 1

Oceanography instrument used to measure conductivity, temperature and pressure (D for depth)

Question 2

Why is conductivity measured by a CTD?

Answer 2

It can be used to determine salinity

Question 3

Why must huge amounts of water be sampled to examine organisms distribution?

Answer 3

Organisms are often distributed heterogeneously

Question 4

In the study by Vargas et al. (2015), where was the greatest diversity found?

Answer 4

In the heterotrophic protist groups, especially those known to be parasites or symbiotic hosts

Question 5

What are some key planktonic players in the ocean?

Answer 5

1. Viruses e.g. CroV
2. Bacteria e.g. Trichodesmium and Prochlorococcus
3. Archaea
4. Photosynthetic protists e.g. diatoms, dinoflagellates and coccolithophores
5. Heterotrophic protists e.g. Foraminifera, Radiolaria and Ciliates

Question 6

How do viruses impact oceans?

Answer 6

• Parasitic, control many autotrophs
• Impact nitrogen cycling, particle size distributions, sinking rates of plankton
• Most abundant biological agent in the ocean

Question 7

Why are bacteria so important in oceans?

Answer 7

They play a major role as decomposers, recycling nutrients and releasing dissolved organic matter (DOM)
Play a role in carbon flux

Question 8

What is the process by which bacteria release nutrients back into water?

Answer 8

1. Organic particles sink
2. Bacterial decay regenerates nutrients
3. Occurs below the photic zone
4. Nutrients carried into deep water

Question 9

What is a diazocyte?

Answer 9

A special nitrogen-fixing cell of the marine cyanobacteria Trichodesmium

Question 10

What is the most abundant photosynthetic organism in the sea?

Answer 10

Prochlorococcus

Question 11

Hotspots of Trichodesmium

Answer 11

Found in areas of warmer currents, where nutrients are low so not many other species could survive

Question 12

What is Trichodesmium limited by? How do they get past it?

Answer 12

Phosphorus

They can use unusual sources of phosphorus - monophosphate esters and phosphonates

Question 13

Example of symbiosis; puffer fish

Answer 13

Contain symbiotic bacteria that produce a deadly toxin called tetrodotoxin - puffer fish and detoxify the toxin

Question 14

Archaea in oceans

Answer 14

• Can make up 20% of prokaryotes in particular regions of the oceans
• Many are extremophiles
• Common in water and sediments, important in coastal waters

Question 15

Distribution of bacteria and archaea

Answer 15

Mainly in photic layer but still present in small amounts in deep oceans
Can be embedded in marine snow deep in oceans

Question 16

How much of oceans biomass do microbes make up

Answer 16

More than 90%

Question 17

Features and name of coccolithophores

Answer 17

Haptophyta
Photosynthetic protist
Calcium carbonate exoskeleton
Important photosynthesisers
Highly reflective so can cause changes in sea surface temperature

Question 18

Diatom name and features

Answer 18

Eukaryotic plankton
Photosynthetic protist
Bacillariophyta
Cell extensions to aid flotation

Question 19

Features and name of dinoflagellate

Answer 19

Photosynthetic protist
Dinophyta
Can bioluminesce
Up to 2 flagella for motility if waters are nutrient depleted

Question 20

Features of Foraminifera

Answer 20

Single called heterotroph
Planktonic and benthic
Occur in animal guts, plankton, sediments and seaweed

Question 21

Feature of Radiolaria

Answer 21

Shells form siliceous sediment on sea floor when they die

Question 22

Ocean virus example

Answer 22

CroV attacks flagellate heterotroph Cafeteria roenbergensis

Question 23

Features of ciliates

Answer 23

Many benthic but may inhabit guts or sea urchins
Some are planktonic
Important in the microbial loop

Question 24

What work by Rumbo et al. (2000) sparks debate about symbiosis

Answer 24

The sea slug eats green algae and breaks down most of the algae but retains the chloroplasts to use for photosynthesis - is this symbiosis or just use of organelles?