Marine ecosystems

Question 1

What are the 3 major groups of marine life?

Answer 1

Plankton

Nekton

Benthos

Question 2

What are marine plant and animal life affected by?

Answer 2

Solar radiation

Temperature

Pressure

Question 3

Describe characteristics of the group ‘Plankton’

Answer 3

Microscopic floating organisms, some photosynthesis and some eat other organisms.

Plankton float in the water and have no ability to propel themselves against a current.

Includes phytoplankton and zooplankton.

Question 4

Describe the characteristics for the group ‘benthos’

Answer 4

Organisms that live on the ocean bottom, some can move and some are stationary.

Benthos include Benthic flora (attached to algae/seaweeds, bottom dwelling diatoms) require light therefore restricted to shallow waters.

Benthic bacteria and animals (mostly invertebrates) live at great depths on ocean floor.

Benthic organisms that live on the ocean bottom are called epifauna and those living within the bottom sediments and called infauna.

Question 5

Describe the characteristics for the group ‘nekton’

Answer 5

Organisms that can swim against a current.

Nekton are active swimmers and include fish, mammals, reptiles and birds.

Question 6

Give some examples of organisms that cross from one lifestyle classification to another. For example being planktonic early in life and bethic later.

Answer 6

Polychaete larva

Brittle star larva

Snail larva

Blue crab larva

Question 7

List all the environmental factors that affect marine ecology

Answer 7

• temperature
• salinity
• pressure
• nutrients
• dissolved gases
• currents
• light
• suspended sediments (water clarity and food source)
• substrate (bottom material)
• river inflow
• tides
• waves (influence corals and seagrass)

Question 8

List the physical and biotic factors which determines which organisms can live/survive there.

Answer 8

Physical factors:

• temperature
• salinity
• tides
• currents
• wind
• wave action
• light
• substrate
• aspect

Biotic factors:

• to be first
• competition
• cooperation
• altering the environment
• predation
• disease
• extremes

Question 9

Give a brief summary of the biology of the continental shelf in terms of primary production.

Answer 9

Although the continental shelf zones comprise only 7.6% of the surface are of the world oceans, they provide 15-30% of the ocean primary production