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Effects of Human Involvement Effects of Human Involvement in the River Ecosystemin the River Ecosystem
Jonathan Sexton
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AustraliaAustralia Water can be a
scarce resource Dam rivers to
create reservoirs 50% of water
stored in ten large reservoirs
Store largest amount of water in reservoirs in the world
Water used for recreation, cities, animals and plants
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Tallowa DamTallowa Dam
Shoalhaven River
43m high, 520m long, 50m wide
Creates a physical barrier
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Tallowa Dam Con’tTallowa Dam Con’tUpstream of dam 10 fish species extinctFish not able to utilize spillwaysCompetition between species decreasedShort term answer = restock fish
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Problems of DamsProblems of Dams
Fish confined to smaller and different habitats
Breeding and water condition changeFood sources and availability changeUpstream and downstream fish look and
behave differently
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Change in PopulationChange in Population Fish accumulate downstream of dam More susceptible to predators Disease spreads rapidly Not able to reproduce at high rates
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Non-Native SpeciesNon-Native Species
Able to gain a footholdCan be a new species or old
species that was present in small numbers
Once a foothold is gained they are able to move into neighboring river systems
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Water FlowWater Flow
Water flow is lessened
Less erosion power
Allows non-native plants to gain foothold
Willows in Snowy River floodplain
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PoliciesPolicies
Water Conservation and Irrigation Commission– Created in 1971– Maximize water usage
Nation Strategy for Ecologically Sustainable Development– Created in 1991– Gave environment an aliquot of total water
Aliquot- least amount of water that the environment can survive with without damage
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Snowy RiverSnowy River
Hydroelectric dam built in 1974Less diversity physically and biologicallyRiver channels narrow
– Only gets 1% of daily flow
Restoration plan– Give the river 27% of yearly flow
More water in the rainy season
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Murray-Darling BasinMurray-Darling Basin
14% of total landmass– Rivers, floodplains and red gum forests
20 different species of water birdsSeasonal flooding has not occurred in many
areas for years
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Changing the Water FlowChanging the Water Flow
2000 entire forest floodedBird populations increasedEgret species breed for first
time since 1975Water cap put in placeBasin needs 40% more water to
stabilize
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IndicatorsIndicatorsAmount of water and its conditionAquatic plantsMicroscopic organismsFish and Birds
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WaterWater
Surface areaSalinityDepth of water
– Influences temperature, water chemistry and light attenuation
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Aquatic PlantsAquatic Plants
Provide shelter and food for mammals, birds, fish and bacteria
Convert CO2 into O2 Not best indicator
– Cattle grazing nearby can trample and eat vegetation
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Microscopic OrganismsMicroscopic Organisms
Include free floating bacteria, biofilms, zooplankton and fungi
Bottom of the food chainHydrological factors affect them
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Fish and BirdsFish and BirdsReproducingAbundanceBirds not best indicator
– Able to fly to new nesting sites– Able to fly far distances in search of food
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ConclusionConclusion
Humans change the environment drasticallyWe are seeing the errors in our ways and
now trying to fix themMore expensive to fix