#26 Australias marine environment

Question 1

what are the properties of sea-water

Answer 1

it is about 4% salt - salt decreases the heat capacity of seawater, it increases its density and lowers its freezing point

Question 2

where are waters more saline / less saline

Answer 2

water salinity will vary throughout locations in the ocean
salinity depends on how much precipitation there is vs. how much evaporation there is
there is more rainfall, and less evaporation at the equator - hence the water is less saline along the equator

Question 3

what determines water salinity

Answer 3

high rainfall, low evaporation = low salinity

low rainfall, high evaporation = high salinity

Question 4

what are thermoclines, what are haloclines, what are pycnoclines?

Answer 4

thermoclines are changes in temperature throughout the depths of the ocean
haloclines are changes in salt concentration throughout the depths of the ocean - generally more saline in deeper areas
pycnoclines are changes in density throughout the depths of the water - generally it is more denser the deeper it is

Question 5

what is the Coriolis effect

Answer 5

earth rotates and creates currents called the coriolis effect. north currents will deflect to the right, south currents will deflect to the left

Question 6

how is convection created

Answer 6

convection occurs from the solar energy from the sun - most energy hits the equator
convection is the hot air travelling up/down to the poles and cooling, then coming back to the centre

Question 7

what are the major ocean currents

Answer 7

north hemisphere: currents move to the right - clockwise

south hemisphere: currents move to the left - anti-clockwise

Question 8

what are the major australian currents and where do they run

Answer 8

east Australia current: runs along the east coast
tasman front: goes past tassie towards NZ
antartic circumpolar current: goes right along the bottom of Aus.
leeuwin current - runs south from indonesia along WA and to SA

Question 9

what is upwelling

Answer 9

• friction from the atmosphere moves water
• water is pushed out
• as water is pushed out the cold nutrient rich water from below will rise up
• upwelling is important for productivity
• upwelling can occur on coastlines
• upwelling can occur when direction of water is going 2 different ways and cold water will rise up inbetween it - equatorial upwelling

Question 10

what does productivity require

Answer 10

nutrients, sunlight, primary producers

Question 11

where are low productivity zones

Answer 11

saltier places, deep ocean, either side of equator

Question 12

where are high productivity zones

Answer 12

near coast, shallow water, nutrient rich environments

Question 13

what are the primary producers

Answer 13

phytoplankton: diatoms and coccolithophores

Question 14

what are the primary consumers? what do they eat?

Answer 14

they eat phytoplankton - primary producers

zooplankton: includes krill, copepods

Question 15

what are secondary and tertiary consumers? what do they eat

Answer 15

secondary consumers eat primary consumers
tertiary consumers eat secondary consumers
shrimp, krill, fish

Question 16

what are the high levels of consumers

Answer 16

large fish, humans, orca, birds, marine, mammals

Question 17

how many trophic levels does the marine food web have

Answer 17

up to 5

more layers than terrestrial systems

Question 18

compare the marine food web to terrestrial food web

Answer 18

in marine food web there is more top consumer biomass than primary consumer biomass
in terrestrial system there is more primary consumer biomass than there is top consumer biomass
in the ocean all the primary producers can be eaten - in the terrestrial environment some of the primary producers cannot be eaten i.e. tree - food is less accessible for terrestrial animals

Question 19

what are intertidal zones and their features

Answer 19

intertidal zone is sometimes exposed to water, some times not covered by water
most things are attached to rocks to cope with waves
need to tolerate salt and sun
be robust and resilient
coral reefs, rock-pools, beaches etc.

Question 20

whats more diverse? sub-tidal reefs in temperate or tropical zone?

Answer 20

temperate zone rocky reefs are more diverse than tropical sub-tidal reef. temperate rocky reef is also more productive

Question 21

what are the features of the south eastern cool temperate zone

Answer 21

• driven by the Antarctic circumpolar current flowing right
• low nutrients and productivity
• some upwellings

Question 22

what are the features of the eastern warm zone

Answer 22

• driven by east australia current

- tropical and cold water mix

Question 23

what are the features of the eastern tropical zone

Answer 23

• great barrier reef
• high species diversity
• barrier and atolll reefs

Question 24

what are the features of the northern tropical zone

Answer 24

• low in nutrients, low in salinity

- strong influence from Indonesian throughflow

Question 25

what are the features of the western tropical zone

Answer 25

• high habitat diversity
• low productivity
• dominated by Indonesian through-flow

Question 26

what are the features of the south western warm temperate zone

Answer 26

• dominated by the low nutrient leeuwin current

- some productivity around corner of WA