Lecture 8 - DA

Question 1

Define eutrophication. Name the largest source for this process.

Answer 1

Increase/overabundance of organic mattier and nutrients in an aquatic environment. The largest source is from atmospheric deposition from combustion.

Question 2

What is a consequence of the high use of fertiliser runoff into coasts?

Answer 2

Migrates to coasts and urban sprawls leading to increased loads of fertiliser near coasts.

Question 3

What percentage of nitrogen and phosphorus inputs to catchments are trapped within? What happens to this percentage?

Answer 3

75%. Remains in the catchment and not exported elsewhere and therefore accumulates, trapped in sediments or recycled.

Question 4

How are nutrients trapped in an estuary?

Answer 4

The lighter surface water runs towards the ocean, while the deeper water below runs towards the river, creating a mixing zone in the estuary.

Question 5

How do plankton take advantage of nutrient trapping in an estuary?

Answer 5

Plankton from the light surface water sink down to the deeper dense water, and remain in the mixing zone.

Question 6

Name 4 consequences of eutrophication.

Answer 6

Excessive blooms of phytoplankton, algal mats, harmful algae
Algae spoil beaches, promoting harmful bacteria growth
Benthic aquatic macrophytes can be lost
Creates hypoxic or anoxic zones in deep waters

Question 7

How does eutrophication create hypoxic or anoxic zones?

Answer 7

The algae and plankton boom uses up a lot of oxygen.

Later turn to detritus, and are consumed by decomposers, who also use oxygen.

Question 8

Define hab.

Answer 8

Harmful algal bloom.

Question 9

What is a consequence of groundwater removal from aquifers near coasts?

Answer 9

Allows intrusion of seawater, altering foodwebs and productivity.

Question 10

What are 4 environmental impacts of introducing an invasive species?

Answer 10

Displacement or extinction of local species
Altering the habitat
Altering the community structure and foodwebs
Spread of harmful species like hab and cholera

Question 11

Name 2 ways ships can accidentally introduce invasive species.

Answer 11

Ballast water, and hull fouling.

Question 12

What is the el nino caused by?

Answer 12

Events due to southern oscillation of high and low pressure systems centres over the western and eastern pacific ocean.

Question 13

What is the pressure over western and eastern pacific oceans like before an el nino under normal conditions? What does this drive?

Answer 13

Low pressure over western pacific, high over eastern pacific.
Drives normal walker circulation cell.

Question 14

Where does it normally rain before an el nino under normal conditions?

Answer 14

Indonesia

Question 15

What are the trade winds and pacific equatorial currents like before an el nino under normal conditions?

Answer 15

Strong trade winds and pacific equatorial currents push warm water to the western pacific, depressing the thermocline.

Question 16

What happens to the pressure centres and circulation cells during an el nino?

Answer 16

They reverse.

Question 17

Where does rainfall move to during an el nino? What happens to some other countries?

Answer 17

Americas

Australia and Indonesia have droughts and fires

Question 18

What happens to trade winds and pacific equatorial currents during an el nino? Which way does warm water flow? What happens to the sea surface height?

Answer 18

They both weaken or reverse.

Warm water flows to the east, and sea surface height increases 20m.

Question 19

What happens to marine productivity in the eastern pacific and why?

Answer 19

Drops due to excess warm water and lack of nutrients.

Question 20

What time of a year does an el nino occur, and how often?

Answer 20

Around Christmas, every 2-7 years.

Question 21

How long can an el nino last?

Answer 21

Several months.

Question 22

What is a la nina? Describe trade winds, water temperature, upwelling, and rainfall status.

Answer 22

The opposite of an el nino.
Cold water temperatures and upwelling extremes in the eastern pacific.
Trade winds exceptionally strong.
Heavy rain and flooding in the western pacific - Indonesia and Australia

Question 23

What percentage of annual climate variation does an el nino account for in Australia?

Answer 23

40%

Question 24

Name 5 unstable climate changes an el nino can cause.

Answer 24

Floods, drought, fluctuating groundwater storage, increased ocean salinity and temperatures.

Question 25

What happens to ocean temperatures during an el nino?

Answer 25

Rises 8*C.

Question 26

What happens to coastal upwelling of cold nutrient rich waters during an el nino?

Answer 26

Stops.

Question 27

What happens to plankton populations during an el nino?

Answer 27

50% reduction.

Question 28

When do la ninas often happen?

Answer 28

Following an el nino, but not always.

Question 29

How much of the worlds coastlines do coral reefs occupy?

Answer 29

1/6

Question 30

What marine ecosystem has the highest diversity?

Answer 30

Coral reefs

Question 31

What 2 protections do coral reefs give to a coast?

Answer 31

Wave energy and storm energy.

Question 32

Name 8 threats to coral reefs.

Answer 32

Climate change - acidification
Reef mining for calcium carbonate
Increased sedimentation
Pollution - oil spills
Dredging
Ship groundings
Overfishing, harmful practices
Tourism/divers

Question 33

How much of a corals nutrients comes from photosynthesis via symbionts?

Answer 33

60-90%

Question 34

Why does coral bleaching occur?

Answer 34

When photosynthetic algae are expelled during unfavourable circumstances, causing them to die.

Question 35

Name 7 factors that can cause a coral to expel its algae.

Answer 35

Higher temperatures
Increased CO2
UV exposure
Reduced salinity
Pollution
Sedimentation
Diseases

Question 36

Describe the adaptive bleaching hypothesis.

Answer 36

Corals are believed to expel their algae as many different strains exist. Expel them in an effort to take in a better strain, but wont find one, so they die.

Question 37

What effect does climate change have on precipitation and evaporation?

Answer 37

They are accelerated.

Question 38

What effect does climate change have on water vapour in the atmosphere, and what effect does this have?

Answer 38

Increases amounts of vapour, contributing to the greenhouse effect.

Question 39

What effect does climate change have on the coasts, and what effect does this have on salinity?

Answer 39

Climate change increases coastal erosion, which reduces salinity in coastal waters.

Question 40

What causes rising sea levels, and name 4 consequences of this.

Answer 40

Melting ice caps and glaciers, as well as thermal expansion of water.
Causes:
Coastal inundation
Loss of property (maldives)
Higher storm-surge flooding
Loss of seawater to inland bodies and groundwater

Question 41

What percentage of anthropogenic CO2 does the ocean absorb?

Answer 41

50%

Question 42

What effect does an acidified ocean due to increased CO2 have on pH and calcium carbonate shells in the ocean?

Answer 42

Reduces pH and may cause dissolution of calcium carbonate shells and skeletons

Question 43

What consequence does climate change have on phenology?

Answer 43

May cause organisms to reproduce too early or too late

Question 44

What effect does climate change have on species biogeography?

Answer 44

Changes to migration patterns, and potential for increase species invasions.