Changing Ecosystems Year 11 Biology Unit 2 – Outcome 2

Changing EcosystemsChanging Ecosystems

Year 11 BiologyYear 11 Biology

Unit 2 – Outcome 2Unit 2 – Outcome 2

Changes in an ecosystem may be due to:Changes in an ecosystem may be due to:– Regular events Regular events Tides and seasonsTides and seasons– Irregular eventsIrregular events FloodsFloods– One off eventsOne off events Oil spillOil spill

Changes in an ecosystem may be natural or Changes in an ecosystem may be natural or be due to human interventionbe due to human intervention

The initial change may involve the living The initial change may involve the living community or the non-living surroundingscommunity or the non-living surroundings

Detecting changes in ecosystems requires Detecting changes in ecosystems requires long term study.long term study.

Instruments such as satellite mounted Instruments such as satellite mounted sensors give us a picture of how sensors give us a picture of how ecosystems are changingecosystems are changing

Dark blue patch is the arctic ozone hole

These photographs, taken in 1928 and 2000, show how South Cascade Glacier in the Washington Cascade Mountains has retreated over time.

Arctic circle 1979

Arctic circle 2003

Red, orange, and brown Red, orange, and brown colouring indicate areas where colouring indicate areas where temperatures measured in temperatures measured in 2000 are warmer than the 2000 are warmer than the average temperature from average temperature from 1951 to 1980. The scale 1951 to 1980. The scale represents degrees in Celsius. represents degrees in Celsius. Negative numbers represent Negative numbers represent cooling, and positive numbers cooling, and positive numbers depict warming.depict warming.

Human Impacts on EcosystemsHuman Impacts on Ecosystems

Flood controlFlood control (damming, levee banks) (damming, levee banks) Fire preventionFire prevention AgricultureAgriculture (land clearing, irrigation, fertilisers) (land clearing, irrigation, fertilisers) MiningMining Industry Industry (generation of wastes)(generation of wastes) UrbanisationUrbanisation (power generation, waste disposal, (power generation, waste disposal,

water storage, transport)water storage, transport) Introduction of exotic speciesIntroduction of exotic species

Human Impacts on EcosystemsHuman Impacts on EcosystemsIntroduction of exotic speciesIntroduction of exotic species

Exotic species are non-nativeExotic species are non-native Impact includesImpact includes

– Exotic species are effective predators on native Exotic species are effective predators on native speciesspecies

– Introduction of new diseasesIntroduction of new diseases– Competition for resourcesCompetition for resources– Changes to the environmentChanges to the environment

Over all this causes displacement and loss Over all this causes displacement and loss of native speciesof native species

Human Impacts on EcosystemsHuman Impacts on EcosystemsIntroduction of exotic species into AustraliaIntroduction of exotic species into Australia

RabbitsRabbits

Several dozen rabbits were brought to a Several dozen rabbits were brought to a property in Victoria in 1856 for hunting property in Victoria in 1856 for hunting purposespurposes

There are now hundreds of millionsThere are now hundreds of millions One female can produce 30 kittens a yearOne female can produce 30 kittens a year Rabbits compete more efficiently than native Rabbits compete more efficiently than native

species and as a consequence have species and as a consequence have displaced many native speciesdisplaced many native species


RabbitsRabbits

Control of rabbits:Control of rabbits:– MyxomaMyxoma virus released in 1950-51. Carried by virus released in 1950-51. Carried by

mosquitoes and rabbit fleas. Initially 99% mosquitoes and rabbit fleas. Initially 99% mortality in some areas but populations became mortality in some areas but populations became resistant.resistant.

– Rabbit calicivirus released in 1995. dramatically Rabbit calicivirus released in 1995. dramatically reduced population from an estimated 300 reduced population from an estimated 300 millionmillion

Rabbit damage


Cane ToadsCane Toads Cane toads are native to South and Central Cane toads are native to South and Central

AmericaAmerica 100 Cane toads were introduced in 1935 to control 100 Cane toads were introduced in 1935 to control

beetles damaging sugar cane beetles damaging sugar cane The toads have no natural predators in Australia The toads have no natural predators in Australia

and preferred not to eat the beetle they were and preferred not to eat the beetle they were introduced to controlintroduced to control

Their range is estimated to be increasing by 35km Their range is estimated to be increasing by 35km per yearper year

Creamy venom cause death to native animals such Creamy venom cause death to native animals such as goannas, dingos, and snakes that eat themas goannas, dingos, and snakes that eat them

Current and predicted Cane toad distribution (2004)

The federal government spend millions each year trying to solve the Cane toad problem


CarpCarp European carp was brought to Australia in the European carp was brought to Australia in the

1870’s.1870’s. It escaped from Victorian fish farms into the It escaped from Victorian fish farms into the

Murray-Darling system in 1960Murray-Darling system in 1960 Carp increase the turbidity of the water resulting in Carp increase the turbidity of the water resulting in

sunlight not being able to penetratesunlight not being able to penetrate This results in plants and aquatic life not being This results in plants and aquatic life not being

able to surviveable to survive They also increase the nutrient level of the water They also increase the nutrient level of the water

resulting in algal bloomsresulting in algal blooms

Biological ControlBiological Control

Using natural enemies (predators, herbivores, Using natural enemies (predators, herbivores, parasites and disease causing organisms)parasites and disease causing organisms)

1.1. Classical biocontrolClassical biocontrol Introducing an offshore natural enemyIntroducing an offshore natural enemy Success – Prickly pear numbers reduced by introduction of Success – Prickly pear numbers reduced by introduction of

cactus mothcactus moth Failure – Cane toadsFailure – Cane toads

2.2. Conservation biocontrolConservation biocontrol Use of naturally occurring agentsUse of naturally occurring agents

3.3. Use of biopesticidesUse of biopesticides Use of naturally occurring agents such as bacteria and fungiUse of naturally occurring agents such as bacteria and fungi

BiotechnologyBiotechnology

Biotechnology generally refers to Biotechnology generally refers to recombining DNA for a specific userecombining DNA for a specific use

Example 1Example 1– Blocking conception in rabbitsBlocking conception in rabbits

Example 2Example 2– Single sex carpSingle sex carp

Block a gene involved in female developmentBlock a gene involved in female development

Human Impacts on EcosystemsHuman Impacts on EcosystemsOver harvestingOver harvesting

Over-harvesting is an unsustainable use of Over-harvesting is an unsustainable use of a biological resourcea biological resource

It is important to know where and when the It is important to know where and when the species breeds, its rate of growth and time species breeds, its rate of growth and time of sexual maturityof sexual maturity

This will reduce risks of over-exploitationThis will reduce risks of over-exploitation

Human Impacts on EcosystemsHuman Impacts on EcosystemsSalinitySalinity

Salinity refers to the Salinity refers to the salt content of water or salt content of water or soilsoil

Excessive salt Excessive salt stresses native stresses native speciesspecies


Dryland salinityDryland salinity– Australia naturally has high salt levels in the soilAustralia naturally has high salt levels in the soil– Native plant species have large root systems to absorb Native plant species have large root systems to absorb

waterwater– Little rain water reaches the ground water supplyLittle rain water reaches the ground water supply– European settlement resulted in native species being European settlement resulted in native species being

cleared and replaced with shallow rooted vegetationcleared and replaced with shallow rooted vegetation– More water reaches the ground water and the water More water reaches the ground water and the water

table rises dissolving salt and bringing it to the surface.table rises dissolving salt and bringing it to the surface.

The clearing of native vegetation species for agriculture and mining has resulted in the water table rising. As it dose it brings the historical salt deposits to the surface. This water can run into streams and rivers or form salt beds on the surface causing plants to die.


Irrigation salinityIrrigation salinity– Irrigation water soaks Irrigation water soaks

through the soil adding through the soil adding to the ground waterto the ground water

– Water table rises Water table rises bringing salt to the bringing salt to the surfacesurface

– Irrigation water dries Irrigation water dries and leaves salt at the and leaves salt at the surfacesurface


Cost of salinity in AustraliaCost of salinity in Australia– More than $130 million of agricultural production is More than $130 million of agricultural production is

lost annually from salinity lost annually from salinity – The area of salt affected land in Western Australia is The area of salt affected land in Western Australia is

increasing at a rate of one football field per hour increasing at a rate of one football field per hour – Increased salinity could cause the extinction of Increased salinity could cause the extinction of

approximately 450 species of native flora and 250 approximately 450 species of native flora and 250 species of invertebrate water fauna in the Western species of invertebrate water fauna in the Western Australian wheat belt Australian wheat belt

– If salinity is not effectively managed within 20 years, If salinity is not effectively managed within 20 years, the salt content in Adelaide’s drinking water may the salt content in Adelaide’s drinking water may exceed World Health Organisation standards exceed World Health Organisation standards

Information from a government web siteInformation from a government web site

Human Impacts on EcosystemsHuman Impacts on EcosystemsDamming and diverting riversDamming and diverting rivers

ResultsResults– Change of water Change of water

temperatures disrupting temperatures disrupting breedingbreeding

– Wetlands dry out due to Wetlands dry out due to lack of flooding – lack of flooding – habitat destructionhabitat destruction

– Fish migration stoppedFish migration stopped

Dam with fish ladders and spillway

Human Impacts on EcosystemsHuman Impacts on EcosystemsDamming and diverting riversDamming and diverting rivers

Snowy River SchemeSnowy River Scheme

The Snowy Mountains Hydroelectric The Snowy Mountains Hydroelectric Scheme was established in 1967Scheme was established in 1967

99% of the natural flow of the river was 99% of the natural flow of the river was diverted at the Jindabyne Damdiverted at the Jindabyne Dam

Habitats down stream were destroyedHabitats down stream were destroyed A restoration process began in 2002. Over a A restoration process began in 2002. Over a

10 year period the flow will be increased to 10 year period the flow will be increased to 21%21%

The Snowy Mountains Scheme consists of:

- sixteen major dams - seven power stations - a pumping station - 225 kilometres of tunnels, pipelines and aqueducts

Human Impacts on EcosystemsHuman Impacts on EcosystemsEutrophicationEutrophication

Accumulation of dissolved Accumulation of dissolved minerals in waterminerals in water

Waste removalWaste removal Farming runoffFarming runoff

Algal blooms multiply in Algal blooms multiply in nutrient rich waternutrient rich water

This reduces light levels This reduces light levels and causes aquatic and causes aquatic grasses to die which in grasses to die which in turn reduced oxygen levelsturn reduced oxygen levels

Cyanobacteria algal Cyanobacteria algal blooms produce toxinsblooms produce toxins

Murray River Algal Bloom

Swan-Canning Estuary Algal Bloom

Natural agents of changeNatural agents of changeFireFire

Australia is a fire prone country and species Australia is a fire prone country and species have had to adapt to thishave had to adapt to this– Mobile organisms fleeMobile organisms flee– Slower organisms burrowSlower organisms burrow– Plant strategies:Plant strategies:

Vegetative reproducersVegetative reproducers Obligate seederObligate seeder

Pomonal – Grampians bushfires 2006

The Elephants Hide – The Grampians

20 months after the fire


Vegetative reproducersVegetative reproducers– Regrow from buds under bark or underground Regrow from buds under bark or underground

stemsstems Rhizomes - BrackenRhizomes - Bracken Epicormic shoots – Eucalyptus (bark burns poorly. Epicormic shoots – Eucalyptus (bark burns poorly.

Epicormic buds are dormant until fire)Epicormic buds are dormant until fire) Lignotubers – Gums (Underground stems)Lignotubers – Gums (Underground stems)

2003 Canberra


Obligate seedersObligate seeders– Plant doesn’t survive but seeds doPlant doesn’t survive but seeds do– Seed coat or fruit splits in the heat allowing the Seed coat or fruit splits in the heat allowing the

seed to germinateseed to germinate


Fire frequencyFire frequency– Frequent fires will reduce diversityFrequent fires will reduce diversity– Obligate seeders need time to germinate and produce Obligate seeders need time to germinate and produce

their own seedstheir own seeds– Controlled burns can not be too frequentControlled burns can not be too frequent

Absence of fireAbsence of fire– Lack of fire means bushland areas can become Lack of fire means bushland areas can become

overgrown. overgrown. – Sunlight can no longer reach grasses. This can result in Sunlight can no longer reach grasses. This can result in

loss of diversity loss of diversity

2002


Aboriginal use of fireAboriginal use of fire– Used for hunting and land management toolUsed for hunting and land management tool– Low intensity fires to reduce litter build upLow intensity fires to reduce litter build up– Next to burnt patches they left unburnt areasNext to burnt patches they left unburnt areas– Grass lands were preservedGrass lands were preserved– Greater biodiversity created Greater biodiversity created

SuccessionSuccession Natural replacement of a community over timeNatural replacement of a community over time Primary successionPrimary succession

– A bare area is colonised by organisms for the first timeA bare area is colonised by organisms for the first time– Eg: Colonisation of larval flows or coastal dunesEg: Colonisation of larval flows or coastal dunes

Secondary successionSecondary succession– Occurs in areas that have been disturbedOccurs in areas that have been disturbed– Eg: Abandoned paddockEg: Abandoned paddock

– Pioneer species Pioneer species first species to become establishedfirst species to become established Survive under harsh conditions and reproduce rapidly (r-Survive under harsh conditions and reproduce rapidly (r-

selection)selection)

Succession stops when a stable community is established. Succession stops when a stable community is established. – Known as the climax communityKnown as the climax community

Primary Succession

Primary Succession of a bog

Secondary Succession

Grassland with secondary succession

RestorationRestoration

Personal levelPersonal level– RecyclingRecycling– CompostingComposting– Thoughtful water useThoughtful water use– Supporting conservation groupsSupporting conservation groups

Council levelCouncil level– Local clean upsLocal clean ups– Providing recycling facilitiesProviding recycling facilities

RestorationRestoration

State government levelState government level– Sewage treatmentSewage treatment– Legislation to protect ecosystemsLegislation to protect ecosystems

Federal governmentFederal government– LegislationLegislation– QuarantineQuarantine– FundingFunding– Liaising industry and environmental groupsLiaising industry and environmental groups

Documents

Changing Ecosystems Year 11 Biology Unit 2 – Outcome 2