1. Changes in ecosystems

2. Dynamic ecosystems
Ecosystems change over time in a variety of ways. They are not STATIC.
Migration
Habitat change (eg. Destruction, pollution)
Introduced species
Fluctuations of climate
Natural seasonal change

3. Primary and secondary changes
Primary change = original change in ecosystem
Secondary changes = the effects of the primary change
Deforestation
Decreased primary production (photosynthesis)
Loss of habitat
Decrease in insect species
Decreased herbivores
Other species affected

4. Reversing negative change
Humans are often involved in reversing negative change
Culling pest species (eg. Kangaroos, foxes, rabbits)
Restoring habitat
Removing/changing chemical concentrations
Creating false habitats
Assisting reproduction in affected species

5. Causes of change Natural Human Flood Fire Plate tectonics
Seasonal change
Migration
Pollution
Introduction of species
Deforestation
Clearing of land

6. Exotic species introduction – Cane Toads
Cane toads were introduced in 1935 to attempt to control the sugarcane beetles affecting our crops. Since, they have flourished in the Australian environment . They can kill native animals with their toxin, and also create competition and habitat destruction.
Now, Cane Toads are often killed by people trying to control the population growth.

7. Exotic species introduction - Rabbits
Rabbits were brought to a single property in Victoria in 1859, for hunting purposes. Many escaped, and their descendents now are pest species across the entire continent. They reproduce quickly, so spread was rapid.
The myxoma virus has been introduced to wipe out populations. It was initially 99% effective, but rabbits now are immune, with about 20% mortality rate. Calici virus was released in 1995, and has reduced the rabbit population by causing haemorrhaging.

8. Fascinating: how we control pest species
Infecting rabbits with a virus that includes a modified gene that stops conception in females
A gene is switched off in the females, so that they can only have male offspring.

9. Overuse of resources Humans often deplete ecosystems of resources
Water
Land
Trees/plants
Fishing

10. Wasting water Parts of Australia have been in drought for 20-30 years
Water levels in Melbourne critical in about Since, reservoirs have been replenished to about 50%
Use of household water decreased significantly between 1990 and 2005 due to better education (among other things)
BUT water use in the mining industry has increased

11. Sustainability
Sustainability = use of resources within a renewable rate
ie. Resources that renew quickly can be used more quickly than those which take many years to form (eg. Fossil fuels)

12. Salinity Salinity is the salting of the earth
Not many plants can live in salty soil
Causes:
Removal of trees
Excessive irrigation
Improved by:
Removing excess water in the ground
Maintaining plantlife
Regulating irrigation

13. Waste disposal Waste must be disposed somewhere, usually in landfill
Effluent and factory chemicals may end up in waterways, which causes problems such as:
Chemicals evaporate and rain back down
Overgrowth of algae etc, which depletes the system of other nutrients

14. Litter
Litter is often only semi-biodegradable: it takes many years to break down
eg. Plastic bags
Made of fossil fuel products (sustainability)
Partially biodegradable
Can choke wildlife, particularly in aquatic habitats

15. Dredging the bay
Port Phillip Bay is being “dredged” (making parts deeper so ships can go through)
Impacts:
Disturbance of marine life
Disturbance of sediment on bottom of Bay may release non-biodegradable chemicals stored there (eg. Iron, pesticides, factory chemicals, arsenic, zinc etc). As these are not biodegradable, they will undergo bioaccumulation through the food chain

16. Natural change: bushfire
The Australian bush is very prone to fire.
Destroys some habitat
New life grows from ash: many Australian plant species REQUIRE fire to germinate their seeds

17. The Global Ecosystem (biosphere)
Global Warming!!! We’re all going to die!! (right?)
The main greenhouse gas is Carbon Dioxide, which is formed and sent into the atmosphere via normal cellular respiration, as well as activities such as burning fossil fuels, deforestation and increased energy consumption.
Planting more trees can help, as they use atmospheric CO2 to photosynthesise.

18. SAC preparation
Using your results table, summarise the changes we’ve seen, why they’ve occurred, and the impact on the rest of the terrarium ecosystem.
You may bring in to the SAC: your results table, up to one page of hand written summary notes.

19. WE ARE DONE!! Complete all quick check, biochallenge, chapter review.
THEN REVISE, REVISE, REVISE!!