#26 Australias marine environment Flashcards
what are the properties of sea-water
it is about 4% salt - salt decreases the heat capacity of seawater, it increases its density and lowers its freezing point
where are waters more saline / less saline
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
what determines water salinity
high rainfall, low evaporation = low salinity
low rainfall, high evaporation = high salinity
what are thermoclines, what are haloclines, what are pycnoclines?
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
what is the Coriolis effect
earth rotates and creates currents called the coriolis effect. north currents will deflect to the right, south currents will deflect to the left
how is convection created
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
what are the major ocean currents
north hemisphere: currents move to the right - clockwise
south hemisphere: currents move to the left - anti-clockwise
what are the major australian currents and where do they run
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
what is upwelling
- 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
what does productivity require
nutrients, sunlight, primary producers
where are low productivity zones
saltier places, deep ocean, either side of equator
where are high productivity zones
near coast, shallow water, nutrient rich environments
what are the primary producers
phytoplankton: diatoms and coccolithophores
what are the primary consumers? what do they eat?
they eat phytoplankton - primary producers
zooplankton: includes krill, copepods
what are secondary and tertiary consumers? what do they eat
secondary consumers eat primary consumers
tertiary consumers eat secondary consumers
shrimp, krill, fish
what are the high levels of consumers
large fish, humans, orca, birds, marine, mammals
how many trophic levels does the marine food web have
up to 5
more layers than terrestrial systems
compare the marine food web to terrestrial food web
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
what are intertidal zones and their features
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.
whats more diverse? sub-tidal reefs in temperate or tropical zone?
temperate zone rocky reefs are more diverse than tropical sub-tidal reef. temperate rocky reef is also more productive
what are the features of the south eastern cool temperate zone
- driven by the Antarctic circumpolar current flowing right
- low nutrients and productivity
- some upwellings
what are the features of the eastern warm zone
- driven by east australia current
- tropical and cold water mix
what are the features of the eastern tropical zone
- great barrier reef
- high species diversity
- barrier and atolll reefs
what are the features of the northern tropical zone
- low in nutrients, low in salinity
- strong influence from Indonesian throughflow
what are the features of the western tropical zone
- high habitat diversity
- low productivity
- dominated by Indonesian through-flow
what are the features of the south western warm temperate zone
- dominated by the low nutrient leeuwin current
- some productivity around corner of WA
